trackball VS pmw3360-breakout

I did lay out a simple carrier board as a direct replacement for the breadboard in a more permanent build, and had a few of them made up through OshPark. It's really basic -- no components, just some traces and solder pads. (My first time trying to use kicad, I think it turned out decent for what it is.)

not quite sure what you are getting at... regarding thumb use, you can always buy used FXes (or new ones if you want a crazy markup). if you want something slightly more modern, there is the cordless FX. the DIY trackball you speak of is publicly available here: https://github.com/monroewilliams/trackball

isnt a scan, but its a 3d printable trackball with roughly similar shape: https://github.com/monroewilliams/trackball

For me, the hand position used with the Logitech Trackman Marble FX was near perfect for reducing hand and wrist stress. Unfortunately that model was discontinued many years ago, and they're now hard to find, expensive, and generally antiquated (PS/2 interface, dodgy early optical sensor, no scroll wheel). This was the main reason I designed and built my own trackball. Its shape was inspired by the Marble FX, although I modeled it from scratch in OpenSCAD.

Of course. 😎

Sources for all the parts I used are listed here, and there's a fairly extensive assembly guide with pictures here.

For my scratch-built trackball project, I used these breakout boards, and based my initial code off of the seller's sample code. His sample is for Arduino. but it's basically pretty straightforward C code that isn't hard to adapt to any microcontroller. For my purposes I needed to run two of the sensors off one microcontroller, so I turned into a C++ class that runs one sensor per instance, and supports a couple different related sensors (ADNS9800 and PMW3360).

The ball-spin mousewheel is a really nice touch, too

Here you go: https://github.com/jfedor2/pmw3360-breakout

A core module just consists of nice!nano and a pmw3360 breakout board by jfedor2 (https://github.com/jfedor2/pmw3360-breakout) which is shown in the last picture. (By the way, jfedor2 has a lot of cool custom trackballs based on RPI which provide lots of ideas.) I'm planning to use this module to apply in various setting, and this was the first prototype to replace my Ploopy Nano.

Outside of the Ploopy, if you haven't checked out u/Jfedor's stuff I highly recommend it. They created an open source rp2040-PMW3360 pcb specifically for creating new kinds of trackballs. I have bunch coming on the way now (It's a little pricier due to the smd components) and the parts to make trackball 7 when I get here. It's bigger (uses a standard billiard ball) but it seems closer to the direction I'd like. /u/azat-dev on here posted a modified Kyria using Jfedor's 3360 breakout but I don't think they can post the files because it uses modified closed source code.

Personally I'd use one of Adafruit's nRF52 Feather boards with an optical sensor breakout like this (this one happens to be mine, but you can find others).

Here's a nice one if you want to order your own from JLPCB: https://github.com/jfedor2/pmw3360-breakout

You're absolutely right and in that spirit I've posted the STLs here and the sensor breakout here.