As I child, I loved playing with little motors. I'd attach them to a shoebox, strap on some wheels, and rig up some rubber bands to make it go.
These small electric motors, which run on low voltage AC or DC power are constructed from nails, wire and scraps of iron and tin.
"One of the simplest forms of an electric motor where small electromagnets cause a tin rotor to spin. It's run on a couple of batteries. The rotor acts like a tiny switch as it wipes against a brush lightly, turning on current momentarily before its arms pass over the electromagnets. The current impulse is just enough to keep the motor spinning."