Automated Sand drawings
I’ve seen these kinds of art devices before – but they are big corporate looking things and run thousands of dollars. “The principles behind them can’t be that complex”, I thought. But there are some tricky bits I didn’t think of before – and this guy does a great walkthrough.
Personally, I would likely have shaved off the bottom part of the marble to create a flat spot and put felt there, so you don’t disturb the lower pattern as much. Also, I wonder if a specialized plexiglass would have worked better instead of glass to help hide the noise.