As usual, everything starts with the PCB design.

Nothing fancy. The minimal SAMD21 schematic with USB, plus six keys with diodes, a LED and a programming header. As usual in my projects the header has staggered pins to allow plugging in a male header without soldering.

The board will use choc switches, because I really like them. In hindsight, I should have designed some kind of a frankenfootprint so that any switch could be used — maybe I will do that in the next version.