ThumbsUp! Huge Trackball v4 (44, or 52.5, or 55/57mm ball, Ambidextrous, Kailh Choc Switches, ZMK, Bluetooth/USB/Dongle)

A wireless/wired ThumbsUp! Trackball v4 for large balls (44mm, 52.5mm, and 55/57mm diameter.)
Source project is here: https://github.com/ak66666/ThumbsUp-Trackball-v4/

Is sold either as (a) a DIY kit, or as (b) a fully built for a ball of the specified size, with switches and caps, without the ball itself.

"DYI Set of PCBs" kit includes six boards - two "base" decks, a sensor carrier board, and three ball mounts: 44mm, 52.5mm, and 55mm (the latter should work for 57mm ball), see below for the assembly manual link.

"DYI PCBs+Parts" kit includes all boards as above plus all components for assembly, except the ball.

Fully assembled board is built for a specified ball size, all components are installed, sensor and lens are soldered on the carrier board, controller is preprogrammed with the default Bluetooth firmware. You only need to add the ball. Only one ball mount plate is provided - for the size you specify.

57mm ball may/should work with 55mm mount. You need to adjust the sensor, bend it in/out to have approx. 2.4 mm between the ball and the lens. (Don't have such a ball to test that, so it is more like an educated guess) The difference between 55mm and 57mm balls is about 0.5mm, should be enough of play in the connector for that. In the fully built copies I use copper wire between the sensor carrier PCB and the middle PCB, so the sensor can be moved for +/- 1mm from its default position. With DYI kit you may use longer wires or offset the sensor carrier with a spacer (e.g. a cardboard piece), or even use some flexible wires and hot glue to achieve the required gap (2.4mm +/- 0.2mm)

This trackball uses a PMW3610 sensor, with ZMK-based firmware provided.
Two firmware versions available - Bluetooth/wired and a wireless with USB dongle.

Trackball is finger-operated, can be used with the button row towards or away from you.
Two slider switches set device orientation and hand used.
That is you can flip a switch and start using it with the left hand, the buttons will be mirrored, and the ball direction will be reversed instantly, without re-programming.
For scrolling - hold one of the keys and rotate the ball, see the video where I use my pinkie to press the key.

Online button configuration through https://ZMK.Studio, no programming required.
For more control - the source code for ZMK configuration is provided.

For buttons it uses Kailh Choc switches in hot-swap sockets.

Power switch disconnects the battery - to save the charge.


To assemble you will need to obtain the following parts: https://github.com/ak66666/ThumbsUp-Trackball-v4/blob/main/Kicad/Trackball/Fabrication/Trackball%20v4%2C%20Parts%20for%20DYI%2C%20Costs.xlsx
Those parts would cost around 40 CAD, you may have some of them laying around already.

Sensor module comes partially pre-assembled, it contains all components except the actual sensor and its lens.

Assembly instructions: https://thumbsupkeyboards.blogspot.com/2025/09/thumbsup-trackball-v3-assembly-steps.html

Firmware source code:
Bluetooth/wired version: https://github.com/ak66666/zmk-config-trackball.v4
Dongle version: https://github.com/ak66666/zmk-config-trackball.v4.dongle

I offer a fully assembled rev. 4 trackball, with switches, battery but without ball. Please specify the size of the ball you want (44, 52 or 55mm), and the Kailh Choc switch types. Options for switches are: Clicky White, Linear Blue or Red.

By default I set it to work over Bluetooth or the cable.
No cable included.

If you want a USB dongle instead of Bluetooth - please add NRF52840 option from this listing, I will program the trackball and the dongle to work together:
https://www.etsy.com/listing/1699462555/thumbsup-keyboard-add-ons-touchpad?variation0=5018160742

Usage instructions:
https://thumbsupkeyboards.blogspot.com/2025/10/thumbsup-trackball-v35-v4-usage.html

DYI kit assembly steps: https://thumbsupkeyboards.blogspot.com/2025/12/thumbsup-trackball-v4-assembly-step.html

Notes for the DYI kit:
You may squeeze the space between the two bottom PCBs. For that you need to remove the spacer from the male MCU connector, and cut or use shorter stand-offs. One of the pictures shows my own copy of this trackball - that's how low you can go.
Alternatively, you may solder the MCU directly to the board, or place is it on top instead of the bottom of the second PCB, just make sure the ball is not getting in the way. I put the orientation and the handiness switches under the middle PCB, just out of convenience. You may place them on top of that board.