Marble Fidget Runner

This does utilize my 12mm/d marble, but you can also scale it up for other balls. I will say that if you plan to use my 12mm/d marble, please glue it together. The speed at which this thing can move the marble is fast enough to cause the marble to split again. I do suggest making the first layer out of PETG to give it a smooth finish, but the profile takes into account that not everyone uses PETG for support, so you will need to shave a little bit on the bottom of the model.