Wintergatan's Unconventional Performance Systems

Hi everyone! In looking for unconventional digital instruments/controllers, I found some videos from a YouTuber I've followed for some time, Wintergatan. He is a musician that builds many different homemade instruments. Two of his most well known creations are the Marble Machine and the Modulin. The videos are linked below! Although the Marble Machine is more of a mechanical instrument than a digital one, I found it interesting to think about how you could make a digital equivalent of the instrument.