If you've ever so much as held the good old-fashioned NES Zapper, you've probably had at least one fantasy about how cool it would be if it was an actual laser gun. Thanks to some modding from the guys over at North Street Labs, it is now.
The custom piece consists of 445nm diode, batteries, a heat sink, and a safety, because its 2W laser will make you go blind in a hurry, that and it can also set things on fire. You'd be ill-advised to build one yourself unless you really know what you're doing, but there is a step-by-step guide that walks you through the build. You're probably just better off watching the video and yelling "pew! pew!" at the screen, though.