How to build a steel shotgun pneumatic cannon

The Steel Pneumatic shotgun is a very simple metal spud cannon, so see how to make it in this video. It is specially designed for C-cell batteries, but will work with any projectile (granted it makes a good seal in the barrel). It is also very easy to construct and disassemble considering it is put together completely by treaded fittings. So, in final, if you make one of these pneumatic gun cannons, you'll have fun for days, weeks... maybe even years.