This is great, in performance or even an installation piece, physical UI elements would be really engaging.
All of the same aesthetic quality of course, I can totally imagine this built to match your hand crafted pulleys.

Gears and drive shafts, are pretty cool.
I bet you could build a similar selection indicator with a pulley system only, which would be even more “in the same aesthetic”, but I think that a wider variation on the mechanical theme like this would probably be more engaging.

Very steam punk still, which I think you said was not specifically what you were going for but it is a celebration of the aesthetics of machinery so I would expect some similarities regardless.

I’ve always wanted to take one of my midi controllers and replace the knobs and buttons with big Frankenstein levers and knife switches. I expect you’ve already watched lots of the classic treatment of machines in movies, There is Metropolis with an eye toward the beauty of machines, but I also like Frankenstein for a little darker, but very dramatic view of technology.