Motors. The word screams of complexity. They're everywhere and in everything, from car engines to airplanes to toys and electric wristwatches. But sometimes the most complex things can be really simple, as in the case of the homopolar motor, where the main point is a magnetic field. The only items you'll need to make a DIY homopolar motor are a AA battery, copper wire and a rare earth neodymium magnet. This tutorial will show you how to build this simple motor.