You should collaborate with this guy on Reddit who made a trackball sanding rig:
https://www.reddit.com/r/functionalprint/comments/ko2vvs/i_d...
https://www.reddit.com/r/functionalprint/comments/kptk0h/ver...
https://www.reddit.com/r/functionalprint/comments/l0g8ml/fin...
for his custom trackballs:
https://www.reddit.com/r/MechanicalKeyboards/comments/knkcnx...
I just finally branched out from software into hobby hardware and I'm eating up these tinkerer subreddits alive. Thanks for a new one.
I impulse-bought an Arduino Uno (well, the much cheaper Elegoo Uno) starter kit and e-ink display and have been working on my own personal-needs Kindle replacement. Wish I did this as a kid or in uni. Oh well, never too late. Having lots of fun.
The only regret is encumbering my minimalist nomad lifestyle with a multimeter, soldering iron kit, and more when my life had, just a month ago, fit into two duffel bags! A 3D printer is off the table at the moment.
Also - consider local maker/hackerspaces if they're available (and, well, probably in a few months time in any event).