The other day I stumbled across this project for a modular keyboard design (modular in the general sense, not as in modular synthesis): https://hackaday.io/project/6737-modular-synthesizer-controller-keyboard-case

It inspired me to keep thinking about a physical keyboard for PolyMod 2. I've recently gotten the hang of 3D printing a bit better, so I decided to prototype a keyboard design in PLA. It's based on the plastic toy keyboard keys that I used in PolyMod 1, but scaled up to be the size of MicroKorg keys (about 8cm long). The springiness comes from a thin strip of plastic between the key and the anchor point.

Each key pushes down on two silicone buttons, the idea being that you'll hit one button first, then the other a few microseconds later, and the time taken will yield a "velocity" value. So far I haven't managed to get this to work reliably, but already this design works fine as a non-velocity-sensitive keyboard, so I'm hopeful! Here are some pictures - I'll release some STL files once I've developed the design a bit more.