PVC air cannons are great, and everyone should build one of these at some point in their life, but what really makes this build exceptional is the valve. [Ben] created a piston valve for this ...

1" x 4" PVC Pipe Nipple 1" Threaded End Caps (x2) 1/2" x 1 1/4" Spring (Approximate size) Washer & Nut to fit the attached Brake Line Fittings Brass Air Tank Valve (Schrader Valve) Compact Bicycle ...