Mi sobrino no para de jugar con el
A very nice design. I had no problems at all with this one. There were several rough spots that stopped the ball bearings. I polished the track and then up everything just worked fine.
Sliced in Cura 4 with a 0.3 hole expansion to help with tolerances , added a brim to help with bed adhesion although probably it wasn't necessary
So well designed to not use more filament than necessary! The interior is hollow and the base has a circular cutout. This is enjoyable to watch and you won't ever have marbles falling out. There is a curve built into the final loop to slow down the balls for the exit ramp.
No problems printing file. Had to grind down some high spots so marble could roll.