Keyboard Builders' Digest / Projects
ArcBoard mk20
The next iteration of Chris Trotter's ArcBoard is here. Mk20 comes with a lot of improvements.
Published December 2, 2025
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Chris Trotter aka crazymittens-r is back with mk20 of his pretty unique ArcBoard. This design isn't for everyone, it was created with the author's fibromyalgia in mind, allowing his hands to stay in a resting position.
Well, something like 1000 hours over 6.5 months, a 650+ page build journal & 8500+ post build thread, dozens (hundreds?) of CAD components, 4? kilograms of prototype plastic printed, 6 Kicad projects, 7 JLC orders, and so…much…learning… (but I got my desk back!) […] You should not build this. Probably mk21 will be much better – crazymittens-r.
It's hard to highlight a single feature, but I like the "paddle keys" between the main keys and thumb cluster.
Features
- 65 keys (6x4+5-ish plus 2x3 'paddle keys')
- MX switches, hotswap
- flexible Cyboard PCBs, hotswap
- many small PCBs with the main one using on-board STM32F405RGTx controller
- 34 mm trackball
- 5-way directional pad
- 3x EC10 encoders
- 2.25" LCD screens
- lots of LEDs
- custom QMK firmware
Resources
- https://github.com/christrotter/qmk_firmware/tree/arcboard-series/keyboards/handwired/arcboard_mk20/
- https://cyboard.digital/products/dactyl-flex-pcbs
- Imgur gallery
Published on Tue 2nd Dec 2025. Featured in KBD #203 (source).
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