https://www.theverge.com/22958439/trackball-diy-building-plo...
> One friend commented that it looked like MS Trackball Explorer, an iconic trackball ... If you didn’t live through the ’90s and have never heard of a trackball, that’s more than understandable. For the uninitiated, a trackball is a pointing device similar to a mouse, except you use a tiny rolling sphere to move your cursor instead of moving the entire device. Trackballs used to be much more commonplace back in the day, and trackball diehards say it can be an easier and more ergonomic way of interfacing with UI, particularly for people with mobility impairments.
> Goofy name aside, the idea motivating Ploopy mirrors something that has been going around in the DIY keyboard community for a while; namely, open-source design and flexible firmware. The files for all the products Ploopy sells are on Github for anyone resourceful enough to have them fabricated, and the device itself runs QMK, one of a few lightweight keyboard firmwares out there.
Patent expired in 2020, https://old.reddit.com/r/Trackballs/comments/g6mneu/the_pate...