Liverandbacon

There are actually several ways of going about that. Kipkay on youtube has one with the blu-ray violet laser diodes, or you can get one of a different wavelength for the same purpose.

Then of course you can buy them, like a blue spyder 3 laser, roughly the size of a flashlight (do make sure you get safety glasses and treat the device like you would a gun).

I also have an "SSY-1" Nd:YAG solid state laser. These were once rangefinders for our military. You can buy them from ebay (from chad andersen of andersen lasers) or meredith insturments. Neat little pulsed laser. There probably is a video on YT.

Then they only get bigger from there.