I'll add my nickel's worth of advice, FWIW -
As someone brand-new to lasers, stay away from "audience scanning" (even at home) until you really understand what you're doing, and you can keep your entry into the hobby much safer, and a bit less complex.
You can do some incredible beam shows with RGB projectors that don't require scanning the beams into the audience.
Once you remove audence scanning from the picture, you really don't need lenses and filters to attenuate your projector output ~
in fact, for overhead beams and graphics, you're much better off without them.
You can make a "safety mask" for your projector by taping a strip of flat-black painted aluminum foil (commercially available as "foil black") across the projector's output aperture to keep beams from accidently shooting into the area where your audience is sitting. Cheap, safe, effective, and a LOT less complicated than experienting with different lense & filter arrangements.
Any other adjustments to output target zones, beam intensity, etc. can be made using controls within your laser software.
Generally, you probably find that for overhead beams - even in a "home venue" environment - you'll want to use every bit of laser power your projector is capable of delivering.
Be sure to leave room in your budget for a small fog / smoke machine ~
You'll really need that to get the full benefit of beam shows.
Good luck, and please post any questions you have.
We've all been where you were at some point, and this forum is a GREAT place to get answers to any questions you might have!!
Randy
RR
Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
1979.
Sweet.....