I Designed This Educational Display to Show Others How Stepper Motors Work.
Print the octagon stator and dodecagon rotor. You can download the 3d printing files here.
Use a compass to determine the poles of your magnets and glue the magnets with the north poles facing outward. If your magnets are strong enough, the compass on some smartphones will show you the polarity of the magnets.
Press fit the bearing into the stator and then press the rotor into the bearing. I was pleasantly surprised how well the bearing press fit into the stator. When 3d printing, holes tend to want to shrink inward and end up smaller than expected so I usually oversize them a bit.