[WillMorr]

I actually attempted this, the idea of a python script that converts a midi track into a marble run is just too good to not try. I printed a large drum with different track structures inside so I could test various "slopes" by changing the speed and it just doesn't work, the balls bounce around too much to get an audible pitch. A less rigid material or a larger bearing would likely work better but I decided to focus on getting the normal version working well.

[m_kos]

I am not surprised you tried given your earlier project :) https://hackaday.com/2022/09/25/this-found-sound-organ-was-m...

Maybe at the bottom your marbles could land on surfaces with different accustic properties. Track selection would determine the surface and release time would determine the timing.

[smusamashah]

Did you try changing thickness of rails instead of bumps to produce different sounds?