I was a car nut long before I became a computer guy...I vaguely recollect something about this. I believe they would have created a series of cardboard template

I was a car nut long before I became a computer guy...I vaguely recollect something about this. I believe they would have created a series of cardboard templates, mirror images for left and right, about one inch apart along the length of the contour, front to back. And then carved the clay to match the templates. Hope this verbal description is clear enough.