um, im too lazy right now to write one of those detailed project outlines so just google or wiki "potato gun" and youll be on your way.
comment with any good design links you may encounter, like this one:
remember, if theres a picture of somebody holding the gun, go by ponytail length. its like the metric measurement of design reliability, since if they have long hair then they probably havent had it blown off by any combustion chamber grenading lately, or at least by my logic.
some things i would like to suggest for design:
-a comfortable trigger, like if we could use the piezoelectric igniter from a utility lighter that would be nice, but really, stealing a gas grill lighter would be much more fun, we would just have to find a good way to mount it.
-one thing i think is a definite safety measure would be to wrap the combustion chamber completely with duct tape, since they do have a nasty tendency to go boom. that way, if it does go boom in our hands we wont be blinded by plastic shrapnel and the explosion might be quieted down to a loud rupture.
so comment all your ideas, no matter how stupid they are! (kiki).