I've actually been wanting to build one of these. For those of you who don't know how they work, pretty much all it is is that you have a power source, two rails for current to go through (hence the name railgun), and then you have a projectile that is conductive. The current creates a magnetic field, and the force generated from the magnetic field shoots the projectile out. Here is a basic layout of the railgun: There are all sorts of theoretical applications for a railgun, such as shooting projectiles into space or even as weaponry. Of course, both of those require a huge amount of energy. The one I'm designing cannot consume that much energy and its more of a homemade experiment. It's a pretty good size and it can at least shoot stuff at about 50 yds (Based on my calculations that is ).