The disc is laser-printed on an HP LaserJet 4 (with duplexer) that I got from FreeCycle. It’s a PostScript program that I run via The GIMP and then print as a 600dpi bit-map. The filled-in sectors on the inner three tracks are done with a Sharpie as required.
The clamp will be replaced by a hinge when I’ve finalised the location of the arm relative to the disc.
There’s more coming: code, schematics, sample audio.
In the Maker Shed: