I'm thinking about submitting this to their site, but this looks like a potential candidate for a printable gun:
 
http://heizerfirearms.com/

For those who don't want (or can't) go to the site, it's a pistol with over-under barrels, available in .45 acp or 9mm.  You can switch out the barrels to use either configuration.
 
It holds 2 in the chamber, and has a spot in the grip that holds two more rounds in a speed strip for easier reloading.  So a max of 4 "easy" shots w/out having to fiddle around in your pocket.  I imagine speed strips might be printable, too?