11 ms·

Teaching LLMs how to solid model

319 points by wgpatrick 1y ago

mclau157 1y ago
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- deleted 1y ago
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_mattb 1y ago
Really cool, I'd love to try something like this for quick and simple enclosures. Right now I have some prototype electronics hot glued to a piece of plywood. It would be awesome to give a GenCAD workflow the existing part STLs (if they exist) and have it roughly arrange everything and then create the 3D model for a case. Maybe there could be a mating/assembly eval in the future that would work towards that?
ein0p 1y ago
I've done this, and printed actual models AIs generated. In my experience Grok does the best job with this - it one shots even the more elaborate designs (with thinking). Gemini often screws up, but it sometimes can (get this!) figure things out if you show it what the errors are, as a screenshot. This in particular gives me hope that some kind of RL loop can be built around this. OpenAI models screw up and can't fix the errors (common symptom: generate slightly different model with the same exact flaws). DeepSeek is about at the same level at OpenSCAD as OpenAI. I have not tried Claude.
- derac 1y ago
  You've got to be a bit more specific, those words can all refer to many models.
  - ein0p 1y ago
    Typically only the most powerful models are worth a try and even then they feel like they aren't capable enough. This is not surprising: to the best of my knowledge none of the current SOTA models was trained to reason about 3D geometry. With Grok there's just one model: Grok3. With OpenAI I used o1 and o3 (after o3 was released). With Google, the visual feedback was with Gemini Pro 2.5. Deepseek also serves only one model. Where there is a toggle (Grok and Deepseek), "thinking" was enabled.
emorning3 1y ago
Wow! As someone that's written openscad scripts manually I can get real excited about this.
isoprophlex 1y ago
Makes you wonder if there is a place in the pipeline for generating G-code (motion commands that run CNC mills, 3d printers etc.) Being just a domestic 3d printer enthousiast I have no idea what the real world issues are in manufacting with CNC mills; i'd personally enjoy an AI telling me which of the 1000 possible combinations of line width, infill %, temperatures, speeds, wall generation params etc. to use for a given print.
- rowanG077 1y ago
  There is some industry usage of AI in G-code generation. But it often requires at least some post processing. In general if you just want a few parts without hard tolerances it can be pretty good. But when you need to churn out thousands it's worth it to go in an manually optimize to squeeze out those precious machine hours.
nohat 1y ago
I tried this a few months back with claude 3.5 writing cadquery code in cline, with render photos for feedback. I got it to model a few simple things like terraforming mars city fairly nicely. However it still involved a fair bit of coaching. I wrote a simple script to automate the process more but it went off the rails too often. I wonder if the models improved image understanding also lead to better spatial understanding.
- cdchhs 1y ago
  how did you feedback the rendered photos or was it a manual copy-paste step?
  - nohat 1y ago
    Just a python script to render then api call with a prompt to check if the render looks right.
rowanG077 1y ago
About a year ago I had a 2D drawing of a relatively simple, I uploaded it to chatgpt and asked it to model it in cadquery. It required some coaching and manual post processing but it was able to do it. I have since moved to solvespace since even after using cadquery for years I was spending 50% of the time finding some weird structure to continue my drawing from. Solvespace is simply much more productive for me.
spmcl 1y ago
I did this a few months ago to make a Christmas ornament. There are some rough edges with the process, but for hobby 3D printing, current LLMs with OpenSCAD is a game-changer. I hadn't touched my 3D printer for years until this project. https://seanmcloughl.in/3d-modeling-with-llms-as-a-cad-luddite/ https://seanmcloughl.in/3d-modeling-with-llms-as-a-cad-luddi...
- dgacmu 1y ago
  This matches my experience having Claude 3.5 and Gemini 2.0-flash generate openSCAD, but I would call it interesting instead of a game changer. It gets pretty confused about the rotation of some things and generally needs manual fixing. But it kind of gets the big picture sort of right. It mmmmayybe saved me time the last time I used it but I'm not sure. Fun experiment though.
- 0_____0 1y ago
  As a MCAD user this makes me feel more confident that my skills are safe for a bit longer. The geometry you were trying to generate (minus bayonet lock, which is actually a tricky thing to make because it relies on elastic properties of the material) takes maybe a few minutes to build in Solidworks or any modern CAD package.
conorbergin 1y ago
Your prompts are very long for how simple the models are, using a CAD package would be far more productive. I can see AI being used to generate geometry, but not a text based one, it would have to be able to reason with 3d forms and do differential geometry. You might be able to get somewhere by training an LLM to make models with a DSL for Open Cascade, or any other sufficiently powerful modelling kernel. Then you could train the AI to make query based commands, such as: // places a threaded hole at every corner of the top surface (maybe this is an enclosure) CUT hole(10mm,m3,threaded) LOCATIONS surfaces().parallel(Z).first().inset(10).outside_corners() This has a better chance of being robust as the LLM would just have to remember common patterns, rather than manually placing holes in 3d space, which is much harder.
- wgpatrick 1y ago
  I definitely agree with your point about the long prompts. The long prompts are primarily an artifact of trying to make an eval where there is a "correct" STL. I think your broader point, text input is bad for CAD, is also correct. Some combo of voice/text input + using a cursor to click on geometry makes sense. For example, clicking on the surface in question and then asking for "m6 threaded holes at the corners". I think a drawing input also make sense as its quite quick to do.
  - eMPee584 1y ago
    Actually XR is great for this, with a good 3D interface two-handed manipulation of objects felt surprisingly useful when I last tried an app called GravitySketch on my pico4..
- Legend2440 1y ago
  There are diffusion models for 3D generation. They make pretty good decorative or ornamental models, like figurines. They are less good for CAD.
GenshoTikamura 1y ago
Oh, poor itty-bitty Skynet won't be able to create Terminators without mastering CAD modelling, so let us totally teach it
alexose 1y ago
As a huge OpenSCAD fan and everyday Cursor user, it seems obvious to me that there's a huge opportunity _if_ we can improve the baseline OpenSCAD code quality. If the model could plan ahead well, set up good functions, pull from standard libraries, etc., it would be instantly better than most humans. If it had a sense of real-world applications, physics, etc., well, it would be superhuman. Is anyone working on this right now? If so I'd love to contribute.
- switchbak 1y ago
  OpenSCAD has some fundamental issues with which folks are well aware. Build123d is a Python alternative that shows promise and seems more capable, and there's others around. Hard to beat the mindshare of OpenSCAD at the moment though.
dave1010uk 1y ago
I 3D printed a replacement screw cap for something that GPT-4o designed for me with OpenSCAD a few months ago. It worked very well and the resulting code was easy to tweak. Good to hear that newer models are getting better at this. With evals and RL feedback loops, I suspect it's the kind of thing that LLMs will get very good at. Vision language models can also improve their 3D model generation if you give them renders of the output: "Generating CAD Code with Vision-Language Models for 3D Designs" https://arxiv.org/html/2410.05340v2 https://arxiv.org/html/2410.05340v2 OpenSCAD is primitive. There are many libraries that may give LLMs a boost. https://openscad.org/libraries.html https://openscad.org/libraries.html
alnwlsn 1y ago
The future: "and I want a 3mm hole in one side of the plate. No the other side. No, not like that, at the bottom. Now make it 10mm from the other hole. No the other hole. No, up not sideways. Wait, which way is up? Never mind, I'll do it myself." I'm having trouble understanding why you would want to do this. A good interface between what I want and the model I will make is to draw a picture, not write an essay. This is already (more or less) how Solidworks operates. AI might be able to turn my napkin sketch into a model, but I would still need to draw something, and I'm not good at drawing. The bottleneck continues to be having a good enough description to make what you want. I have serious doubts that even a skilled person will be able to do it efficiently with text alone. Some combo of drawing and point+click would be much better. This would be useful for short enough tasks like "change all the #6-32 threads to M3" though. To do so without breaking the feature tree would be quite impressive.
- wgpatrick 1y ago
  Yeah - I fully agree with this POV. From a UX/UI POV, I think this is where things are headed. I talk about this a bit at the end of the piece.
- itissid 1y ago
  > and I want a 3mm hole in one side of the plate. No the other side. No, not like that, at the bottom. Now make it 10mm from the other hole. No the other hole. No, up not sideways. One thing that is interesting here is you can read faster than TTS to absorb info. But you can speak much faster than you can type. So is it all that typing that's the problem or could be just an interface problem? and in your example, you could also just draw with your hand(wrist sensor) + talk. As I've been using agents to code this way. Its way faster.
  - alnwlsn 1y ago
    Feels a bit like being on a call with someone at the hardware store, about something that you both don't know the name for. Maybe the person on the other end is confused, or maybe you aren't describing it all that well. Isn't it easier to take a picture of the thing or just take the thing itself and show it to someone who works there? Harder again to do that when the thing you want isn't sold at the store, which is probably why you're modeling it in the first place. Most of the mechanical people I've met are good at talking with their hands. "take this thing like this, turn it like that, mount it like this, drill a hole here, look down there" and so on. We still don't have a good analog for this in computers. VR is the closest we have and it's still leagues behind the Human Hand mk. 1. Video is good too, but you have to put in a bit more attention to camerawork and lighting than taking a selfie.
monoid73 1y ago
this is one of the more compelling "LLM meets real-world tool" use cases i've seen. openSCAD makes a great testbed since it's text-based and deterministic, but i wonder what the limits are once you get into more complex assemblies or freeform surfacing. curious if the real unlock long-term will come from hybrid workflows, LLMs proposing parameterized primitives, humans refining them in UI, then LLMs iterating on feedback. kind of like pair programming, but for CAD.
- wgpatrick 1y ago
  Complex assemblies completely fall on their face. It's pretty fun/hilarious to ask it to do something like: "Make a mid-century modern coffee table" -- the result will have floating components, etc. Yes to your thought about the hybrid workflows. There's a lot of UI/UX to figure out about how to go back and forth with the LLM to make this useful.
  - coderenegade 1y ago
    This is kind of the physical equivalent of having the model spit out an entire app, though. When you dig into the code, a lot of it won't make sense, you'll have meat and gravy variables that aren't doing anything, and the app won't work without someone who knows what they're doing going in and fixing it. LLMs are actually surprisingly good at at codeCAD given that they're not trained on the task of producing 3d parts, so there's probably a lot of room for improvement. I think it's correct that new workflows will need to be developed, but I also think that codeCAD in general is probably the future. You get better scalability (share libraries for making parts, rather than the data), better version control, more explicit numerical optimization, and the tooling can be split up (i.e. when programming, you can use a full-blown IDE, or you can use a text editor and multiple individual tools to achieve the same effect). The workflow issue, at least to me, is common to all applications of LLMs, and something that will be solved out of necessity. In fact, I suspect that improving workflows by adding multiple input modes will improve model performance on all tasks.
jmcpheron 1y ago
It's so cool to see this post, and so many other commenters with similar projects. I had the same thought recently and designed a flexible bracelet for pi Day using openscad and a mix of some the major AI providers. I'm cool to see other people are doing similar projects. I'm surprised how well I can do basic shapes and open scad with these AI assistants. https://github.com/jmcpheron/counted-out-pi https://github.com/jmcpheron/counted-out-pi
itomato 1y ago
I spent #Marchintosh trying to get a usable Apple EMate Stylus out of ChatGPT and OpenSCAD. I took measurements. I provided contours. Still have a long way to go. https://github.com/itomato/EmateWand https://github.com/itomato/EmateWand
adamweld 1y ago
A recent Ezra Klein Interview[0] mentioned some "AI-Enabled" CAD tools used in China. Does anyone know what tools they might be talking about? I haven't been able to find any open-source tools with similar claims. >I went with my colleague Keith Bradsher to Zeekr, one of China’s new car companies. We went into the design lab and watched the designer doing a 3D model of one of their new cars, putting it in different contexts — desert, rainforest, beach, different weather conditions. >And we asked him what software he was using. We thought it was just some traditional CAD design. He said: It’s an open-source A.I. 3D design tool. He said what used to take him three months he now does in three hours. [0] https://www.nytimes.com/2025/04/15/opinion/ezra-klein-podcast-thomas-friedman.html https://www.nytimes.com/2025/04/15/opinion/ezra-klein-podcas...
- throwaway314155 1y ago
  Happy to be corrected but this sounds like the kind of bullshit that crops up from time to time confusing "old" AI with generative AI. Not that I don't believe it's possible. I just think the alternative (that it's bullshit) is more likely.
- sota_pop 1y ago
  Sounds like he could have been using an implementation of stable-diffusion+control-net. I’ve used Automatic1111, but I understand comfyUI and somethingsomethingforge are more modern versions.
ariwilson 1y ago
I'm a great user for this problem as I just got a 3D printer and I'm no good at modeling. I'm doing tutorials and printing a few things with TinkerCAD now, but my historic visualization sense is not great. I used SketchUp when I had a working Oculus Quest which was very cool but not sure how practical it is. Unfortunately I tried to generate OpenSCAD a few times to make more complex things and it hasn't been a great experience. I just tried o3 with the prompt "create a cool case for a Pixel 6 Pro in openscad" and, even after a few attempts at fixing, still had a bunch of non-working parts with e.g. the USB-C port in the wrong place, missing or incorrect speaker holes, a design motif for the case not connected to the case, etc. It reminds me of ChatGPT in late 2022 when it could generate code that worked for simple cases but anything mildly subtle it would randomly mess up. Maybe someone needs to finetune one of the more advanced models on some data / screenshots from Thingiverse or MakerWorld?
mertleee 1y ago
Really curious how you got these tools to talk so elegantly to each-other? Is this an MCP implementation or?
yapyap 1y ago
ah yes, let’s interface all our programs with text
howon92 1y ago
> To my surprise, Zoo’s API didn’t perform particularly well in comparison to LLMs generating STLs by creating OpenSCAD This is interesting. As foundational models get better and better, does having proprietary data lose its defensibility more?
- jessfraz 1y ago
  Zoo co-founder here. Our product is still pre-v1. But getting to v1 very soon. We actually built a whole new CAD kernel from the ground up. I say this because we can't actually train on models the CAD engine does not yet support. Just 2 weeks ago we shipped csg boolean operations to the CAD engine. This unlocked new data to train our model on that use those operations. So its actually fair to say at the time he used our model we using about 2% of the data we actually have. Once we can use more and more the ability of the model will only get better.
geor9e 1y ago
I get that CAD interfaces are terrible - but if I imagine the technological utopia of the future - using the english language as the interface sounds terrible no matter how well you do it. Unless you are paraplegic and speaking is your only means of manipulating the world. I much prefer the direction of sculpting with my hands in VR, pulling the dimensions out with a pinch, snapping things parellel with my fine motor control. Or sketching on an iPad, just dragging a sketch to extrude is to it's normal, etc etc. These UIs could be vastly improved. I get that LLMs are amazing lately, but perhaps keep them somewhere under the hood where I never need to speak to them. My hands are bored and capable of a very high bandwidth of precise communication.
- klysm 1y ago
  I’m not sure that CAD interfaces are terrible, it’s just hard work
  - geor9e 1y ago
    That's what they would have said about drafting tools in the 1880s, command line AutoCAD in the 1980s. Try to imagine the 2080s, or the most visionary sci-fi movie about that future - one of those movies where people look back and says "wow they were close!". Suppose a character wanted to get an idea for a three-dimensional form from their brain onto some medium. They're not going to be clicking a plane, clicking sketch, clicking some lines, tapping the dimension hotkey, twisting their spacemouse a bit with their left hand, clicking extrude, dragging, tapping into their numpad the height, etc etc. We use the clunky interface of our age.
    - klysm 1y ago
      Perhaps, but the hard part about CAD to me isn’t the interference, but rather the specification of the geometries and the dependency structure. That’s the hard part that’s hiding in the background. It’s kind of like getting stuck on the syntax of a programming language instead of being worried about the semantics
niemandhier 1y ago
This reminds me of using llms for LaTex. They will get you to 80% fast, The last 20% to match what is in your head are hard. If you never walked the long path you you probably won’t manage to go the last few steps.
karolist 1y ago
I wanted to use this process (LLM -> OpenSCAD) a few months ago to create custom server rack brackets (ears) for externally mounting water-cooling radiator of the server I am building. I ended up learning about 3D printing, using SolidWorks (it has great built-in tutorials) and did this the old fashioned way. This process may work for refining parts against very well known objects, i.e. iPhone, but the amount of refinement, back and forth and verbosity needed, the low acceptance rate - I do not believe we're close to using these tools for CAD.
fxtentacle 1y ago
Wow, this entire thing reads like a huge "stay away" sign to me. The call to action at the end is: "Try out Text-to-CAD in our Modeling App" But that's like the last thing I want to do. Even when I'm working with very experienced professionals, it's really hard to tell them what exactly I want to see changed in their 3D CAD design. That's why they usually export lots of 2D drawings and then I will use a pencil to draw on top of it and then they will manually update the 3D shape to match my drawn request. The improvement that I would like to see in affordable CAD software is that they make it easier to generate section views and ideally the software would be able to back-propagate changes from 2D into the 3D shape. Maybe one day that will be possible with multimodal AI models, but even then the true improvement is going to be in the methods that the AI model uses internally to update the data. But trying to use text? That's like bringing a knife to a gunfight. It's obviously the wrong modality for humans to reason about shapes. Also, as a more general comment, I am not sure that it is possible to introduce a new CAD tool with only subscription pricing. Typically, an enclosure design will go through multiple variations over multiple production runs in multiple years. That means it's obvious to everyone that you need your CAD software to continue working for years into the future. For a behemoth like Autodesk, that is believable. For a startup with a six month burn rate, it's not. That's why people treat startups with subscription pricing like vaporware.
rcarmo 1y ago
As someone who enjoys doing CAD and spends a fair amount of time doing contortions to get OpenSCAD to do relatively simple things like bevels and chamfers, I’d say this is interesting because of the model ranking, but ultimately pointless because LLMs do not really have a mental model of things like CSG and actual relative positioning - they can do simple boxes and cylinders with mounting holes, but that’s about it.
acyou 1y ago
I think if you could directly tokenize 3D geometry and train an LLM on 3D models directly, you might get somewhere. In order to prompt it, you would need to feed it a 3D model(s), and prompts and it could give you back a different 3D model. This has been done to some extent with generative modeling pre-LLM, but I don't know of any work that takes LLM techniques applied to language and applies them to "tokenizing" 3D geometry. I suspect NVIDIA is probably working very hard on this exact problem for graphics applications. For mechanical design, 3D modeling is highly integrative, inputs are from a vast array of poorly specified inputs with a high amount of unspecified and fluid contextual knowledge, and outputs are not well defined either. I'm not convinced that mechanical design is particularly well suited to pairing with LLM workflow. Certain aspects, sure. But 3D models and drawings that we consider "well-defined" are still usually quite poorly defined, and from necessity rely heavily on implicit assumptions. The geometry of machine threads, for example. Are you going to have a big computer specify the position of each of the atoms in the machine thread? Even the most detailed CAD/CAM packages have thread geometry extremely loosely defined, to the point of listing the callout, and not modeling any geometry at all in many cases. It would just be very difficult to feed enough contextual knowledge into an LLM to have the knowledge it needs to do mechanical design. Therein lies the main problem. And I will stress that it's not a training problem, it's a prompt problem, if that makes sense.
flimflamm 1y ago
It would be interesting to see how far one could get with fine tuning and RL. One could for example take free scad models, give 2D pictures from different angles and ask LLM to recreate the 3D design in scad language. Then compare volumetrically how close they are and provide feedback. Once that is done then ask LLM to create a prompt and compare outputs etc..
adius 1y ago
I think it would be better to use a an existing programming language for CAD so that the LLM has more training data already. Therefore im working on LuaCAD (https://github.com/ad-si/LuaCAD https://github.com/ad-si/LuaCAD), which is a Lua frontend for OpenSCAD.
deleted 1y ago
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bdcravens 1y ago
Most of the 3D printing model repositories offer financial incentives for model creators, as they are usually owned by manufacturers who want to own as much of the ecosystem as possible. (Makerworld, Printables, etc) Widespread AI generation obviously enables abuse of those incentives, so it'll be interesting to see how they adjust to this. (It's already a small problem, with modelers using AI renderings that are deceptive in terms of quality)
mattegan 1y ago
While this all is super cool, and I don't want to downplay TFAs efforts - I'm kind of at my wit's end here. You've gotten me at a bad time. I use a computer every day to do electrical (and sometimes, poorly) mechanical CAD. Getting frustrated with/at software is a daily occurrence, but CAD software is some of the worst. Egg on my face, maybe, but for MCAD I use Fusion360. It's constantly bugging out - and I'm not even talking about the actual modeling workflow or tools! I'll get windows disappearing and floating above other windows. It won't work if you don't install updates within a few days of their release. If I go offline it pops banners in my face. Sometimes, duplicate copies of itself open up, presumably because the updater put a new binary somewhere on my machine that spotlight indexed while I had the previous version running... Sometimes you can't delete files in the cloud because they're referenced by... other deleted files?? A few weeks ago I installed an update like a good boy, and it literally broke the functionality of _being able to click on things_ in the model tree. On the ECAD side, I use KiCAD for most personal/professional projects these days - very, very few complaints there, actually. However, a new client is using Altium, so here we go... My primary machine is a M3 Max MBP, and I know it's running through the ARM translation layer inside Parallels, but Altium was completely unusable! Opening the component library or moving the explorer window took multiple seconds. I dusted off an X1 Carbon, which admittedly is 6-ish years old, but it was even worse there! You must understand, for schematic editing, this software's primary use is to drag rectangles around and connect them with lines. How difficult can this be? I had to get a new Windows machine just to be able to navigate around Altium without constant stuttering. Honestly, even on this new machine it's still slower than I'd like. This software is upwards of $5k a year for a single seat license! [1] I grew up using Macromedia Studio 8, which I installed from a box of CDs, watching my father use his Pentium 4 machine to make complex block diagrams in Visio 2002. In the mid 2000s he was laying out PCBs in PADS without any issues on a laptop! Now a single tab of Lucidchart takes more memory than my old PC could even address, I can't resize the godforsaken library viewer window in Altium on a machine with 16 cores, and if I want to change the settings on my mouse I have to sit through Logitech asking me if I want to log in and join the mouse community to share usage tips? What the hell is going on!? So, forgive me, and not to go full Casey Muratori, but when I see companies like AdamCAD trying to push this new paradigm, I just can't handle it. Can we please, please, please, just go back to making decent software that enables me to do my work without constant hassle? I don't give a single damn about the AI features if I can't count on the software opening and being usable day in and day out. I lose actual time each and every week to dealing with software issues and I'm so so over it. [1] $5k for a single site license, of which to attain, you'll have to sit in a sales meeting for a half hour, during which the sales rep tells you that - technically the EULA establishes a 0.5 mile radius for your "single site" but - don't worry - using it at home 3.5 miles away is totally okay, he's not going to make you buy two $5k licenses - thank god!

319 points by wgpatrick 1y ago

mclau157 1y ago

[flagged]

deleted 1y ago
[deleted]

_mattb 1y ago

Really cool, I'd love to try something like this for quick and simple enclosures. Right now I have some prototype electronics hot glued to a piece of plywood. It would be awesome to give a GenCAD workflow the existing part STLs (if they exist) and have it roughly arrange everything and then create the 3D model for a case. Maybe there could be a mating/assembly eval in the future that would work towards that?

ein0p 1y ago

I've done this, and printed actual models AIs generated. In my experience Grok does the best job with this - it one shots even the more elaborate designs (with thinking). Gemini often screws up, but it sometimes can (get this!) figure things out if you show it what the errors are, as a screenshot. This in particular gives me hope that some kind of RL loop can be built around this. OpenAI models screw up and can't fix the errors (common symptom: generate slightly different model with the same exact flaws). DeepSeek is about at the same level at OpenSCAD as OpenAI. I have not tried Claude.

derac 1y ago
You've got to be a bit more specific, those words can all refer to many models.
- ein0p 1y ago
  Typically only the most powerful models are worth a try and even then they feel like they aren't capable enough. This is not surprising: to the best of my knowledge none of the current SOTA models was trained to reason about 3D geometry. With Grok there's just one model: Grok3. With OpenAI I used o1 and o3 (after o3 was released). With Google, the visual feedback was with Gemini Pro 2.5. Deepseek also serves only one model. Where there is a toggle (Grok and Deepseek), "thinking" was enabled.

emorning3 1y ago

Wow! As someone that's written openscad scripts manually I can get real excited about this.

isoprophlex 1y ago

Makes you wonder if there is a place in the pipeline for generating G-code (motion commands that run CNC mills, 3d printers etc.) Being just a domestic 3d printer enthousiast I have no idea what the real world issues are in manufacting with CNC mills; i'd personally enjoy an AI telling me which of the 1000 possible combinations of line width, infill %, temperatures, speeds, wall generation params etc. to use for a given print.

rowanG077 1y ago
There is some industry usage of AI in G-code generation. But it often requires at least some post processing. In general if you just want a few parts without hard tolerances it can be pretty good. But when you need to churn out thousands it's worth it to go in an manually optimize to squeeze out those precious machine hours.

nohat 1y ago

I tried this a few months back with claude 3.5 writing cadquery code in cline, with render photos for feedback. I got it to model a few simple things like terraforming mars city fairly nicely. However it still involved a fair bit of coaching. I wrote a simple script to automate the process more but it went off the rails too often. I wonder if the models improved image understanding also lead to better spatial understanding.

cdchhs 1y ago
how did you feedback the rendered photos or was it a manual copy-paste step?
- nohat 1y ago
  Just a python script to render then api call with a prompt to check if the render looks right.

rowanG077 1y ago

About a year ago I had a 2D drawing of a relatively simple, I uploaded it to chatgpt and asked it to model it in cadquery. It required some coaching and manual post processing but it was able to do it. I have since moved to solvespace since even after using cadquery for years I was spending 50% of the time finding some weird structure to continue my drawing from. Solvespace is simply much more productive for me.

spmcl 1y ago

I did this a few months ago to make a Christmas ornament. There are some rough edges with the process, but for hobby 3D printing, current LLMs with OpenSCAD is a game-changer. I hadn't touched my 3D printer for years until this project. https://seanmcloughl.in/3d-modeling-with-llms-as-a-cad-luddite/ https://seanmcloughl.in/3d-modeling-with-llms-as-a-cad-luddi...

dgacmu 1y ago
This matches my experience having Claude 3.5 and Gemini 2.0-flash generate openSCAD, but I would call it interesting instead of a game changer. It gets pretty confused about the rotation of some things and generally needs manual fixing. But it kind of gets the big picture sort of right. It mmmmayybe saved me time the last time I used it but I'm not sure. Fun experiment though.
0_____0 1y ago
As a MCAD user this makes me feel more confident that my skills are safe for a bit longer. The geometry you were trying to generate (minus bayonet lock, which is actually a tricky thing to make because it relies on elastic properties of the material) takes maybe a few minutes to build in Solidworks or any modern CAD package.

conorbergin 1y ago

Your prompts are very long for how simple the models are, using a CAD package would be far more productive. I can see AI being used to generate geometry, but not a text based one, it would have to be able to reason with 3d forms and do differential geometry. You might be able to get somewhere by training an LLM to make models with a DSL for Open Cascade, or any other sufficiently powerful modelling kernel. Then you could train the AI to make query based commands, such as: // places a threaded hole at every corner of the top surface (maybe this is an enclosure) CUT hole(10mm,m3,threaded) LOCATIONS surfaces().parallel(Z).first().inset(10).outside_corners() This has a better chance of being robust as the LLM would just have to remember common patterns, rather than manually placing holes in 3d space, which is much harder.

wgpatrick 1y ago
I definitely agree with your point about the long prompts. The long prompts are primarily an artifact of trying to make an eval where there is a "correct" STL. I think your broader point, text input is bad for CAD, is also correct. Some combo of voice/text input + using a cursor to click on geometry makes sense. For example, clicking on the surface in question and then asking for "m6 threaded holes at the corners". I think a drawing input also make sense as its quite quick to do.
- eMPee584 1y ago
  Actually XR is great for this, with a good 3D interface two-handed manipulation of objects felt surprisingly useful when I last tried an app called GravitySketch on my pico4..
Legend2440 1y ago
There are diffusion models for 3D generation. They make pretty good decorative or ornamental models, like figurines. They are less good for CAD.

GenshoTikamura 1y ago

Oh, poor itty-bitty Skynet won't be able to create Terminators without mastering CAD modelling, so let us totally teach it

alexose 1y ago

As a huge OpenSCAD fan and everyday Cursor user, it seems obvious to me that there's a huge opportunity _if_ we can improve the baseline OpenSCAD code quality. If the model could plan ahead well, set up good functions, pull from standard libraries, etc., it would be instantly better than most humans. If it had a sense of real-world applications, physics, etc., well, it would be superhuman. Is anyone working on this right now? If so I'd love to contribute.

switchbak 1y ago
OpenSCAD has some fundamental issues with which folks are well aware. Build123d is a Python alternative that shows promise and seems more capable, and there's others around. Hard to beat the mindshare of OpenSCAD at the moment though.

dave1010uk 1y ago

I 3D printed a replacement screw cap for something that GPT-4o designed for me with OpenSCAD a few months ago. It worked very well and the resulting code was easy to tweak. Good to hear that newer models are getting better at this. With evals and RL feedback loops, I suspect it's the kind of thing that LLMs will get very good at. Vision language models can also improve their 3D model generation if you give them renders of the output: "Generating CAD Code with Vision-Language Models for 3D Designs" https://arxiv.org/html/2410.05340v2 https://arxiv.org/html/2410.05340v2 OpenSCAD is primitive. There are many libraries that may give LLMs a boost. https://openscad.org/libraries.html https://openscad.org/libraries.html

alnwlsn 1y ago

The future: "and I want a 3mm hole in one side of the plate. No the other side. No, not like that, at the bottom. Now make it 10mm from the other hole. No the other hole. No, up not sideways. Wait, which way is up? Never mind, I'll do it myself." I'm having trouble understanding why you would want to do this. A good interface between what I want and the model I will make is to draw a picture, not write an essay. This is already (more or less) how Solidworks operates. AI might be able to turn my napkin sketch into a model, but I would still need to draw something, and I'm not good at drawing. The bottleneck continues to be having a good enough description to make what you want. I have serious doubts that even a skilled person will be able to do it efficiently with text alone. Some combo of drawing and point+click would be much better. This would be useful for short enough tasks like "change all the #6-32 threads to M3" though. To do so without breaking the feature tree would be quite impressive.

wgpatrick 1y ago
Yeah - I fully agree with this POV. From a UX/UI POV, I think this is where things are headed. I talk about this a bit at the end of the piece.
itissid 1y ago
> and I want a 3mm hole in one side of the plate. No the other side. No, not like that, at the bottom. Now make it 10mm from the other hole. No the other hole. No, up not sideways. One thing that is interesting here is you can read faster than TTS to absorb info. But you can speak much faster than you can type. So is it all that typing that's the problem or could be just an interface problem? and in your example, you could also just draw with your hand(wrist sensor) + talk. As I've been using agents to code this way. Its way faster.
- alnwlsn 1y ago
  Feels a bit like being on a call with someone at the hardware store, about something that you both don't know the name for. Maybe the person on the other end is confused, or maybe you aren't describing it all that well. Isn't it easier to take a picture of the thing or just take the thing itself and show it to someone who works there? Harder again to do that when the thing you want isn't sold at the store, which is probably why you're modeling it in the first place. Most of the mechanical people I've met are good at talking with their hands. "take this thing like this, turn it like that, mount it like this, drill a hole here, look down there" and so on. We still don't have a good analog for this in computers. VR is the closest we have and it's still leagues behind the Human Hand mk. 1. Video is good too, but you have to put in a bit more attention to camerawork and lighting than taking a selfie.

monoid73 1y ago

this is one of the more compelling "LLM meets real-world tool" use cases i've seen. openSCAD makes a great testbed since it's text-based and deterministic, but i wonder what the limits are once you get into more complex assemblies or freeform surfacing. curious if the real unlock long-term will come from hybrid workflows, LLMs proposing parameterized primitives, humans refining them in UI, then LLMs iterating on feedback. kind of like pair programming, but for CAD.

wgpatrick 1y ago
Complex assemblies completely fall on their face. It's pretty fun/hilarious to ask it to do something like: "Make a mid-century modern coffee table" -- the result will have floating components, etc. Yes to your thought about the hybrid workflows. There's a lot of UI/UX to figure out about how to go back and forth with the LLM to make this useful.
- coderenegade 1y ago
  This is kind of the physical equivalent of having the model spit out an entire app, though. When you dig into the code, a lot of it won't make sense, you'll have meat and gravy variables that aren't doing anything, and the app won't work without someone who knows what they're doing going in and fixing it. LLMs are actually surprisingly good at at codeCAD given that they're not trained on the task of producing 3d parts, so there's probably a lot of room for improvement. I think it's correct that new workflows will need to be developed, but I also think that codeCAD in general is probably the future. You get better scalability (share libraries for making parts, rather than the data), better version control, more explicit numerical optimization, and the tooling can be split up (i.e. when programming, you can use a full-blown IDE, or you can use a text editor and multiple individual tools to achieve the same effect). The workflow issue, at least to me, is common to all applications of LLMs, and something that will be solved out of necessity. In fact, I suspect that improving workflows by adding multiple input modes will improve model performance on all tasks.

jmcpheron 1y ago

It's so cool to see this post, and so many other commenters with similar projects. I had the same thought recently and designed a flexible bracelet for pi Day using openscad and a mix of some the major AI providers. I'm cool to see other people are doing similar projects. I'm surprised how well I can do basic shapes and open scad with these AI assistants. https://github.com/jmcpheron/counted-out-pi https://github.com/jmcpheron/counted-out-pi

itomato 1y ago

I spent #Marchintosh trying to get a usable Apple EMate Stylus out of ChatGPT and OpenSCAD. I took measurements. I provided contours. Still have a long way to go. https://github.com/itomato/EmateWand https://github.com/itomato/EmateWand

adamweld 1y ago

A recent Ezra Klein Interview[0] mentioned some "AI-Enabled" CAD tools used in China. Does anyone know what tools they might be talking about? I haven't been able to find any open-source tools with similar claims. >I went with my colleague Keith Bradsher to Zeekr, one of China’s new car companies. We went into the design lab and watched the designer doing a 3D model of one of their new cars, putting it in different contexts — desert, rainforest, beach, different weather conditions. >And we asked him what software he was using. We thought it was just some traditional CAD design. He said: It’s an open-source A.I. 3D design tool. He said what used to take him three months he now does in three hours. [0] https://www.nytimes.com/2025/04/15/opinion/ezra-klein-podcast-thomas-friedman.html https://www.nytimes.com/2025/04/15/opinion/ezra-klein-podcas...

throwaway314155 1y ago
Happy to be corrected but this sounds like the kind of bullshit that crops up from time to time confusing "old" AI with generative AI. Not that I don't believe it's possible. I just think the alternative (that it's bullshit) is more likely.
sota_pop 1y ago
Sounds like he could have been using an implementation of stable-diffusion+control-net. I’ve used Automatic1111, but I understand comfyUI and somethingsomethingforge are more modern versions.

ariwilson 1y ago

I'm a great user for this problem as I just got a 3D printer and I'm no good at modeling. I'm doing tutorials and printing a few things with TinkerCAD now, but my historic visualization sense is not great. I used SketchUp when I had a working Oculus Quest which was very cool but not sure how practical it is. Unfortunately I tried to generate OpenSCAD a few times to make more complex things and it hasn't been a great experience. I just tried o3 with the prompt "create a cool case for a Pixel 6 Pro in openscad" and, even after a few attempts at fixing, still had a bunch of non-working parts with e.g. the USB-C port in the wrong place, missing or incorrect speaker holes, a design motif for the case not connected to the case, etc. It reminds me of ChatGPT in late 2022 when it could generate code that worked for simple cases but anything mildly subtle it would randomly mess up. Maybe someone needs to finetune one of the more advanced models on some data / screenshots from Thingiverse or MakerWorld?

mertleee 1y ago

Really curious how you got these tools to talk so elegantly to each-other? Is this an MCP implementation or?

yapyap 1y ago

ah yes, let’s interface all our programs with text

howon92 1y ago

> To my surprise, Zoo’s API didn’t perform particularly well in comparison to LLMs generating STLs by creating OpenSCAD This is interesting. As foundational models get better and better, does having proprietary data lose its defensibility more?

jessfraz 1y ago
Zoo co-founder here. Our product is still pre-v1. But getting to v1 very soon. We actually built a whole new CAD kernel from the ground up. I say this because we can't actually train on models the CAD engine does not yet support. Just 2 weeks ago we shipped csg boolean operations to the CAD engine. This unlocked new data to train our model on that use those operations. So its actually fair to say at the time he used our model we using about 2% of the data we actually have. Once we can use more and more the ability of the model will only get better.

geor9e 1y ago

I get that CAD interfaces are terrible - but if I imagine the technological utopia of the future - using the english language as the interface sounds terrible no matter how well you do it. Unless you are paraplegic and speaking is your only means of manipulating the world. I much prefer the direction of sculpting with my hands in VR, pulling the dimensions out with a pinch, snapping things parellel with my fine motor control. Or sketching on an iPad, just dragging a sketch to extrude is to it's normal, etc etc. These UIs could be vastly improved. I get that LLMs are amazing lately, but perhaps keep them somewhere under the hood where I never need to speak to them. My hands are bored and capable of a very high bandwidth of precise communication.

klysm 1y ago
I’m not sure that CAD interfaces are terrible, it’s just hard work
- geor9e 1y ago
  That's what they would have said about drafting tools in the 1880s, command line AutoCAD in the 1980s. Try to imagine the 2080s, or the most visionary sci-fi movie about that future - one of those movies where people look back and says "wow they were close!". Suppose a character wanted to get an idea for a three-dimensional form from their brain onto some medium. They're not going to be clicking a plane, clicking sketch, clicking some lines, tapping the dimension hotkey, twisting their spacemouse a bit with their left hand, clicking extrude, dragging, tapping into their numpad the height, etc etc. We use the clunky interface of our age.
  - klysm 1y ago
    Perhaps, but the hard part about CAD to me isn’t the interference, but rather the specification of the geometries and the dependency structure. That’s the hard part that’s hiding in the background. It’s kind of like getting stuck on the syntax of a programming language instead of being worried about the semantics

niemandhier 1y ago

This reminds me of using llms for LaTex. They will get you to 80% fast, The last 20% to match what is in your head are hard. If you never walked the long path you you probably won’t manage to go the last few steps.

karolist 1y ago

I wanted to use this process (LLM -> OpenSCAD) a few months ago to create custom server rack brackets (ears) for externally mounting water-cooling radiator of the server I am building. I ended up learning about 3D printing, using SolidWorks (it has great built-in tutorials) and did this the old fashioned way. This process may work for refining parts against very well known objects, i.e. iPhone, but the amount of refinement, back and forth and verbosity needed, the low acceptance rate - I do not believe we're close to using these tools for CAD.

fxtentacle 1y ago

Wow, this entire thing reads like a huge "stay away" sign to me. The call to action at the end is: "Try out Text-to-CAD in our Modeling App" But that's like the last thing I want to do. Even when I'm working with very experienced professionals, it's really hard to tell them what exactly I want to see changed in their 3D CAD design. That's why they usually export lots of 2D drawings and then I will use a pencil to draw on top of it and then they will manually update the 3D shape to match my drawn request. The improvement that I would like to see in affordable CAD software is that they make it easier to generate section views and ideally the software would be able to back-propagate changes from 2D into the 3D shape. Maybe one day that will be possible with multimodal AI models, but even then the true improvement is going to be in the methods that the AI model uses internally to update the data. But trying to use text? That's like bringing a knife to a gunfight. It's obviously the wrong modality for humans to reason about shapes. Also, as a more general comment, I am not sure that it is possible to introduce a new CAD tool with only subscription pricing. Typically, an enclosure design will go through multiple variations over multiple production runs in multiple years. That means it's obvious to everyone that you need your CAD software to continue working for years into the future. For a behemoth like Autodesk, that is believable. For a startup with a six month burn rate, it's not. That's why people treat startups with subscription pricing like vaporware.

rcarmo 1y ago

As someone who enjoys doing CAD and spends a fair amount of time doing contortions to get OpenSCAD to do relatively simple things like bevels and chamfers, I’d say this is interesting because of the model ranking, but ultimately pointless because LLMs do not really have a mental model of things like CSG and actual relative positioning - they can do simple boxes and cylinders with mounting holes, but that’s about it.

acyou 1y ago

I think if you could directly tokenize 3D geometry and train an LLM on 3D models directly, you might get somewhere. In order to prompt it, you would need to feed it a 3D model(s), and prompts and it could give you back a different 3D model. This has been done to some extent with generative modeling pre-LLM, but I don't know of any work that takes LLM techniques applied to language and applies them to "tokenizing" 3D geometry. I suspect NVIDIA is probably working very hard on this exact problem for graphics applications. For mechanical design, 3D modeling is highly integrative, inputs are from a vast array of poorly specified inputs with a high amount of unspecified and fluid contextual knowledge, and outputs are not well defined either. I'm not convinced that mechanical design is particularly well suited to pairing with LLM workflow. Certain aspects, sure. But 3D models and drawings that we consider "well-defined" are still usually quite poorly defined, and from necessity rely heavily on implicit assumptions. The geometry of machine threads, for example. Are you going to have a big computer specify the position of each of the atoms in the machine thread? Even the most detailed CAD/CAM packages have thread geometry extremely loosely defined, to the point of listing the callout, and not modeling any geometry at all in many cases. It would just be very difficult to feed enough contextual knowledge into an LLM to have the knowledge it needs to do mechanical design. Therein lies the main problem. And I will stress that it's not a training problem, it's a prompt problem, if that makes sense.

flimflamm 1y ago

It would be interesting to see how far one could get with fine tuning and RL. One could for example take free scad models, give 2D pictures from different angles and ask LLM to recreate the 3D design in scad language. Then compare volumetrically how close they are and provide feedback. Once that is done then ask LLM to create a prompt and compare outputs etc..

adius 1y ago

I think it would be better to use a an existing programming language for CAD so that the LLM has more training data already. Therefore im working on LuaCAD (https://github.com/ad-si/LuaCAD https://github.com/ad-si/LuaCAD), which is a Lua frontend for OpenSCAD.

deleted 1y ago

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bdcravens 1y ago

Most of the 3D printing model repositories offer financial incentives for model creators, as they are usually owned by manufacturers who want to own as much of the ecosystem as possible. (Makerworld, Printables, etc) Widespread AI generation obviously enables abuse of those incentives, so it'll be interesting to see how they adjust to this. (It's already a small problem, with modelers using AI renderings that are deceptive in terms of quality)

mattegan 1y ago

While this all is super cool, and I don't want to downplay TFAs efforts - I'm kind of at my wit's end here. You've gotten me at a bad time. I use a computer every day to do electrical (and sometimes, poorly) mechanical CAD. Getting frustrated with/at software is a daily occurrence, but CAD software is some of the worst. Egg on my face, maybe, but for MCAD I use Fusion360. It's constantly bugging out - and I'm not even talking about the actual modeling workflow or tools! I'll get windows disappearing and floating above other windows. It won't work if you don't install updates within a few days of their release. If I go offline it pops banners in my face. Sometimes, duplicate copies of itself open up, presumably because the updater put a new binary somewhere on my machine that spotlight indexed while I had the previous version running... Sometimes you can't delete files in the cloud because they're referenced by... other deleted files?? A few weeks ago I installed an update like a good boy, and it literally broke the functionality of _being able to click on things_ in the model tree. On the ECAD side, I use KiCAD for most personal/professional projects these days - very, very few complaints there, actually. However, a new client is using Altium, so here we go... My primary machine is a M3 Max MBP, and I know it's running through the ARM translation layer inside Parallels, but Altium was completely unusable! Opening the component library or moving the explorer window took multiple seconds. I dusted off an X1 Carbon, which admittedly is 6-ish years old, but it was even worse there! You must understand, for schematic editing, this software's primary use is to drag rectangles around and connect them with lines. How difficult can this be? I had to get a new Windows machine just to be able to navigate around Altium without constant stuttering. Honestly, even on this new machine it's still slower than I'd like. This software is upwards of $5k a year for a single seat license! [1] I grew up using Macromedia Studio 8, which I installed from a box of CDs, watching my father use his Pentium 4 machine to make complex block diagrams in Visio 2002. In the mid 2000s he was laying out PCBs in PADS without any issues on a laptop! Now a single tab of Lucidchart takes more memory than my old PC could even address, I can't resize the godforsaken library viewer window in Altium on a machine with 16 cores, and if I want to change the settings on my mouse I have to sit through Logitech asking me if I want to log in and join the mouse community to share usage tips? What the hell is going on!? So, forgive me, and not to go full Casey Muratori, but when I see companies like AdamCAD trying to push this new paradigm, I just can't handle it. Can we please, please, please, just go back to making decent software that enables me to do my work without constant hassle? I don't give a single damn about the AI features if I can't count on the software opening and being usable day in and day out. I lose actual time each and every week to dealing with software issues and I'm so so over it. [1] $5k for a single site license, of which to attain, you'll have to sit in a sales meeting for a half hour, during which the sales rep tells you that - technically the EULA establishes a 0.5 mile radius for your "single site" but - don't worry - using it at home 3.5 miles away is totally okay, he's not going to make you buy two $5k licenses - thank god!