I haven’t posted a Rube Goldberg/Pythagoras Switch/Marble Run video for ages, so I thought I would show you two short ones today. Both were made by Kaplamino.
You can find more of Kaplamino’s videos here. (He does domino runs too.)
If you want to try building a marble run using fidget spinners this weekend, but don’t have any in the house and can’t get to a dollar store, you can find on line instructions for making several different kinds from paper. This one seems to me to have optimal weight and mobility. You could probably use a T-pin or pushpin to hold it in place, instead of building the axle.