I added a little electric motor to the minitracker [previously] and made a loop disk of my favorite bit from The Vapours by Anna Meredith. Minitracker even makes a tiny accidental light show, a tiny bit like the music video.
The mechanical tracker was too unreliable, so I made a nearly-as-unreliable optical version.
A precious useless object.
It’s playing the first digits of Pi.
spatula + guitar string + contact microphone