This is a keyboard shell for a six-key chord keyboard, based on the Microwriter and Quinkey designs from the 80's. These keyboards allow one-handed touch-typing and are great for use by people with brittle bones or unreliable hand control as the fingers stay in one position and only press down with the finger pads for all characters. The hand rests on the palm swell.
Code for the USB keyboard is put on a ATmega32u-equipped Arduino clone is available from https://github.com/VikOlliver/Microwriter , and the only other electronic components are a USB lead and 6 standard lever microswitches.
The microswitches used were ZHAOYAO lever microswitches measuring 12.8x5.8mm and had a 6.5mm high body, a common size used for 3D printers. 10 pack on DX here: https://www.dx.com/p/zhaoyao-10-pieces-1a-125v-ac-limit-switch-lever-parts-mk7-mk8-3d-printer-parts-tripod-micro-switches-2024499
The objects should print without support, and the included support infill is easily snipped at to mount whatever size Arduino clone you use.
4 Small woodscrews attach the base. It is recommended (but not essential) that you ballast the case with clay, shot and hot glue, whatever, to make it more stable and stick non-slip pads on the bottom.
The keycaps can be stuck to the (usually bent) levers in the microswitches, taking care not to let the keycap rub on the sides of the switch hole. I use CAPA resin.
It should flip for left-handed use.
If you wish to use or modify this item for a vaguely commercial purpose that is a good cause, please contact me and I will explain my reasoning and workarounds.