Hmmmmm....smoke machine.......
My friend will be walking around so he'll need a portable source, maybe I could build the smoke generator INTO the gun.....
So lasers are less dangerous if the beam is less focused?
Could I get away with a blue beam if I managed to widen it? Would that be less dangerous?
AFAIK you'd be better off using high powered blue LEDs with some sort of optics to have a better 'beam' than going with lasers at all.
Cost would be about 10x less than blue lasers, about 1000x less dangerous, and you would have an easier time making the light more 'visible' from the sides and around the prop without burning 6 holes in the carpet every time you shoot it.
As for IR : Greens use IR 'pump' diodes that excite a crystal that produces the green light. Blues and reds don't have IR leakage.
405nm looks purple, not blue... To get that color you'd need 473nm (which is *very* expensive) or 488nm (never seen any portable).
445nm would be closer but still much "deeper" and less cyan - you can find some 50-150mW single mode 445nm lasers out there for about 50-100 USD.
100mW isn't safe but it's a lot safer than 1W. Take a lot of care while using it! Don't target anything reflective, don't point at crowds and use goggles if you intend to look at the dot up close or burn stuff.
473nm is getting cheaper, if you're willing to spend $300 per unit on the 473's I'd say go for it. 488nm diodes are out there... however the cheapest they come by right now are ~$1700 per diode...
I've often wanted a laser that matches the color of the dead space ones... I've narrowed it down to a wavelength between 473nm and 488nm, so my best guess would be around 480nm... which won't exist in any small package unless it's a development diode or a miracle diode.
Atomicrox has everything right, go for single mode 450nm orsam diodes if you want a blue color in a moderately safe power range. Just to add, the beam is much nicer on the single mode diodes. If you're going to take it around with you PLEASE be careful with it, don't let yourself or your friends shine it around crowds and whatnot, no need to make the hobby suffer over lack of care, 150mW or 1000mW, it's as damaging as getting stabbed in the eye from a direct hit from one of these.
There's probably going to be a second group buy setting the price at around $37 per diode coming up in a month or so... if you're up for less waiting time but a higher price ($54/diode?) look at DTR's shop.