To give a little idea for what I'm aiming for: I want to make a prop laser gun. It doesn't have to actually do anything, but I've decided it'd be awesome if it did. I could use a 2-5W blue laser diode like some people who make awesome contraptions with lasers show on YouTube, but I'd frankly rather not get arrested. Therefore my questions are: Is possible to have a compact collimator that would actually create a rough beam from, say, one of the high luminosity LED's? Just narrow and divergent enough to create the effect on 10-20 meters. If the former is at all possible, would a beam of sufficient brightness (like a high luminosity LED) scatter and be visible without introducing smoke (in dimmed stuffy room), like a high power laser? So just to reiterate, I'm not asking "can I make a laser out of an LED", rather can I make something that would look like a video game laser weapon and be relatively harmless (not permanently blind people).