A Rail gun is an awesome, dangerous weapon - and a cool science experiment.
Using electromagnets and super capacitors, you can launch pocket change at 100's of feet per second. What could possibly go wrong?
Well, a lot actually. With that much electricity, it's easy to melt wires and catch things on fire. But building a rail gun is for the good of science, so it's worth the risk.
Tip: If you want to launch a penny at the speed of a bullet, you'll need 650 Amps. Make sure to get thick enough wire!