I needed another corded mouse and this time around I thought of @PKL@mastodon.social and @pronk@mastodon.social instead of Logitech's shareholders. These guys make open source mice among other open source hardware under the brand Ploopy. You can order one from them, assembled or as a kit, or you could print and build it entirely by yourself.
The mouse itself is pretty great. Coming from a long line of Logitech (MX518/G5/G500/G502), it's a bit larger than what I'm used to but I think I'm getting accustomed to it.
Here's another shot of it:
I bought a Ploopy Thumb a few years ago. I assembled it myself, and was pleasantly surprised at how easy it was (when actually following the instructions).
The small button on the right has broken twice, which wasn't a problem because I just downloaded the stl file and reprinted the button assembly.
I wanted horizontal scrolling, so I used QMK to make the trackball a scroll wheel when the right side button is pressed (that may explain the faster button wear). It was surprisingly easy, and there was even a comment in the source code pointing out which line I should modify for horizontal scrolling support. I guess they expected people to want this feature.
The price is high, but I don't expect to buy another mouse unless my needs change. The open source hardware and software is excellent, making repairability 10/10. The edges of the buttons are slightly rough, but I have the 3d printing files, so I get to choose what material it's made of and what post processing / smoothing is used. It hasn't bothered me enough to do anything about it.
While I can't recommend a trackball mouse to anyone, I can recommend Ploopy. It's one of the few products that I feel like I actually own.
What I really want is this, but with a trackpad instead of a trackball.
They do have a trackpad, but not in this shape.
I was surprised when I started using the Steamdeck. The Steamdeck's trackpad felt almost identical to my trackball mouse, and it took effectively no time to get used to it.
The advantage of a trackball over a trackpad is that you can spin the ball for high movement speed, then stop it after a set time for fairly accurate distance. A trackball (or trackpad) will never be as accurate as a regular moue, but it is surprisingly usable (after a few months or practice).
I've used several trackballs, but they have all been seriously uncomfortable for me and my specific brand of RSI. My current "mouse" is a Steam Controller, but using it one-handed isn't great due to the uneven weight distribution. I also have much better accuracy using a trackpad vs a trackball.
Ideally, I just want a Steam Controller cut in half with a more confortable grip that doesn't dig into my palm.