This very simple electric motor is called a homopolar motor because the magnetic field does not change direction or strength. With only three parts, it is probably the simplest motor you can possibly make.
Copper Wire, 18 Gauge
1) Place the neodymium magnet on the negative terminal of the battery. The magnet used here was 0.5 inches in diameter and 0.25 inches thick. Anything near that size will work, but normal ceramic magnets are too weak. You can buy neodymium magnets at K&J Magnetics.
2) If your copper wire is insulated you need to remove the insulation. Bend the wire into any shape you want. It needs to make good contact with the positive terminal of the battery as well as with the circumference of the magnet. Watch the video for two examples.
3) Balance the copper piece on top of the battery and make any needed adjustments until it spins easily.