Check out the Goodwatch from Travis Goodspeed https://github.com/travisgoodspeed/goodwatch https://github.com/travisgoodspeed/goodwatch It is a"replacement ci

Check out the Goodwatch from Travis Goodspeed https://github.com/travisgoodspeed/goodwatch https://github.com/travisgoodspeed/goodwatch It is a"replacement circuit board for the Casio 3208 module, used in the Casio CA-53W and CA-506 calculator watches" and very neighborly.