Paintballs can be "shot" though a simple blowgun.

If you want to do it cheap, four foot of conduit will do nicely, but
remember to blow, not suck!

http://www.protectiondepot.com/blowgun_accessories4.asp is a 'merkin
company, but you should be able to get them from anywhere local that does
skirmish.

http://www.geocities.com/blowgunhunter/index.html for ideas, then do a
couple of searches on your favorite search engine.

Peter