This 41-button Arduino keyboard PCB is a stepping stone to his next project, a pair of two-way texting machines. (Which is nice, because we were totally going to suggest that).

The early keyboards use a Teensy, while the Mark 13 (and the final Kickstarted keyboard) use an Arduino Micro. Mark 6. A 3D-printed base (12 hours to print), 3D-printed hand plates (3-4 hours each ...