This is something I have done like 20 years ago in wood, now a new version in plastic! What is this? Long time ago I was trying to build a perpetual motion device with magnet, unfortunately it rotate but like from 0 to 359 degrees :)... Its start slow and go super fast until it stop. How it work? A spiral like rotor with small magnets all around the rotor. You need an external magnet (stator) to attract the magnets and the rotor start to spin. They are maybe a way to move the rotor with some kind of mechanical hack like spring or anything to move the magnet that attract the rotor for a short period of time or to use a electro-magnet that cancel the magnet force when the rotor need to restart another round.. The scad file are parametric so you can build it at any size with the magnet you want to use. Anyway have fun with it, I will print one when my printer will be ready to print. I will also update the scad file over time if needed. Right now no STL files are provided since you can generate then using the SCAD file, you can change everything like magnet size etc. it is better this way for now. You can stack multiple rotors. In the image I only show one rotor, when mine will be printed, I will use 2 rotors at 180 degrees from each others. The SCAD use 2 skateboards ball bearing, to eliminate friction, so you need a 8mm or 5/16 inch rod. Note that you have 2 choices to put the magnets on the rotor, you can glues them or (my choice) is to put other magnets behind the rotor... All the magnets are facing the same pole, if they are all south, the stator magnet will face north, this design work best in attraction mode not repulsion.