Here's a working, homebrewed 1MW laser pistol that can fire through a steel razor-blade and possibly other objects as well. If you want to make one of your own, the creator will help you find the parts and get it all together.
German hacker [Patrick Priebe] recently constructed a laser pulse gun that looks so good, it could have easily come off a Hollywood movie set. Its sleek white and black exterior adds intrigue, but offers little warning as to how powerful the gun actually is.
Fitted with a Q-switched Nd:YAG laser, it fires off a 1 MW blast of infrared light once the capacitors have fully charged. The duration of the laser pulse is somewhere near 100ns, so he was unable to catch it on camera, but its effects are easily visible in whatever medium he has fired upon. The laser can burst balloons, shoot through plastic, and even blow a hole right through a razor blade.