A PCB-based finger-operated trackball, inspired by Elecom EX-G left hand trackball, Ploopy Nano trackball, and my own ThumbsUp! Trackball v3.
Off-the-shelf ProMicro-style MCUs is considered:
- nice!nano v2 (and clones) with ZMK-based firmware - wireless/wired/BT/dongle.
34 mm ball, same as in Elecom EX-G, or 44 mm, or 52.5mm as in Elecom Huge, or 55mm balls.
57mm ball may work - sensor needs to be adjusted to provide 2.4 mm distance from the lens to the ball surface.
For bearings - uxcell 2.5mm Ceramic Bearing Balls, ZrO2 Zirconium Oxide Ball, again, the same as used to improve my Elecom trackballs. Bearings to be implanted into PCBs, no 3D-printed ball shroud/holder.
A few buttons scattered on top of the boards, not sure about their bindings yet, so let's say 6 of them at least + 4 for reset/ZMK.Studio/BT Reset/BT Next. I.e. let's keep the buttons of v3 for now. (As of rev.2 there are 8 "large" buttons, 3 programmable and 1 reset low-profile buttons.)
Rev.2 with 55 mm Ball:
Rev.1 with 44 mm Ball:
USB dongle (n!n in a case):
Other pictures in Photos folder.
Bluetooth/wired connection: https://github.com/ak66666/zmk-config-trackball.v4
USB dongle: https://github.com/ak66666/zmk-config-trackball.v4.dongle
https://www.etsy.com/ca/listing/4390959934/thumbsup-trackball-v4-44-or-525-or-55mm
These steps from Trackball v3 are mostly applicable. https://thumbsupkeyboards.blogspot.com/2025/09/thumbsup-trackball-v3-assembly-steps.html