I made alternate keycaps with OpenScad for my keypad but in the end I chose to stick with what I had before. I wanted the buttons to have smaller profiles and be the same colour. At first I tried to make a complicated clip like the injection molded ones that came with the set, but that failed as 3d printed material is not suited for that purpose. Instead I made keycaps that held on with friction. That worked, but they were hard to take off again and they ended up being uglier than the injection molded ones.