Air pistol

I was thinking of building one of theses first.^
im not sure how to do it thought help? i know how to buld the air pistol part.

i was thinking of something i could screw on or something, so i can fire then put another paint ball down the chamber and screw on a new tank.

lot of waist for 1 paint ball... I would consider a golf ball shooter or something. Just get some PVC and adapt it to whatever sizes you need. Cause using one of those air cylinders (not cheap) for 1 paintball isn't very cost effective.

i think it would be great if you could attach it to your wrist it be a concealed assassination thinger XD just walk by some one and BAM their covered in paint and have a nasty welt lol

lol i would refill it, i didnt really exeplan well, i would bluid something like one of those co2 things and put 100 psi behind it, then screw it off, and reload and refill.

You're using all of the CO2 for 1 shot? That's a bit much. Those small chambers there pack a punch, plus you can't necessarily "screw on a new one". A pin pokes a hole in the top, thus releasing the CO2 inside. If you want a small paintball gun, look into a Zeus or TPX.

i think it would be great if you could attach it to your wrist it be a concealed assassination thinger XD just walk by some one and BAM their covered in paint and have a nasty welt lol

That would hurt like a ****.
On that note you could assassinate someone from 600 yards!

if the aim is to make a mini one, couldn't you canabalize the trigger and valve mechanisms from a larger gun and put them on a much smaller mounting? that'd also stop it using all the gas at once. (thinking of the gun from assassins creed 2 heh)