Nick Thatcher’s compact coilgun uses a coil of copper wire along the barrel to launch its projectile. It’s powered by 15 photoflash capacitors juiced up by 2 AAAs. Of course the power of this gun is very much in question, the super dark video on the site doesn’t show a whole lot. It appears, however, to be able to punch through cardboard at a very close range.
Regardless, this is a nicely executed design with a beautiful finished product.