How to Make a Coaxial Air Cannon

This video shows how I make a compact 2" bore air cannon with a coaxial piston valve. To understand how these valves work examine the third animation in the following link:
http://www.spudfiles.com/forums/piston-valves-explained-visually-t8157.html
I also go into more detail of how these cannons function in a video I made many years ago, showing how to build a smaller version using these same principles:
http://youtu.be/9oARDyn4WwE

Warning: It is specifically against manufacturer recommendations to use PVC to contain pressurized air. This video is solely for education and entertainment purposes.

The parts used in this cannon are as follows:
(1) 3' length of 3" diameter pressure rated PVC pipe
(1) 3'2" length of 2" diameter pressure rated PVC pipe
(1) 1/2" PVC ball valve
(1) 1/2" x 2" long threaded PVC pipe nipple
(1) 1 1/2" to 1/2" threaded PVC reducer
(1) 3" to 1 1/2" PVC reducer
(1) 3" PVC coupling
(1) 3" female threaded adapter
(1) 3" male threaded adapter
(1) 3" to 2" PVC reducer
(4) 1" long self tapping screws
(1) brass air compressor tank valve
(2) 3" galvanized steel gas vent tee caps
(1) 3" rubber washer or sheet rubber
(1) 3" tank to bowl rubber gasket

Other supplies and tools needed:
PVC Primer & Cement
Epoxy
Super Glue
TFE Pipe Thread Paste
Coarse and fine Sandpaper
Bench Grinder or Metal Files
Drill & Bits
Bicycle Pump or Air Compressor

Thanks for watching!