An ambitious maker has built a partly 3D-printed railgun that can fire aluminum or graphite projectiles at over 250 meters per second (560 mph). No, this isn't Quake, but it's no janky, all-plastic gun, either. The "handheld" weapon houses six capacitors that weigh 20 pounds and deliver over 1,800 joules of energy per shot. And it indeed works just like a full-sized railgun, using parallel electrodes to fire an "armature" bullet. The creator, David Wirth, added an Arduino Uno R3 to monitor charging levels, temperature and other factors, and tweaked the rails after he noticed "plasma damage."