I found a tank full of airbrush propellant from testors and was thinking of trying your design to see if it would work. The tank Im thinking of is a 6 oz. tank fullof air but there is no PSI rating on it. How, when you fill the tank from the bike pump, do you know when it is full before the can explodes(unlikely but possible)? This is a pic of the tank I was considering.
By the way: Where did you get the valve and the nipple that you attached to the tank and how exactly did you attach them?