The gun consists of a combustion chamber made of 1&1/2" PVC with a screw cap fitting on the end. The combustion chamber is then connected to the barrel by several fittings of 1/2" PVC out of the other end. I took apart a long barbecue lighter, and salvaged the sparker assembly. I cut down the wires, and epoxied them into a hole in the combustion chamber. The other end of the sparker assembly becomes my trigger. To fire the gun, a projectile is placed in the barrel. Then I unscrew the cap on the combustion chamber, spray a small amount of hairspray into it, and then put the cap back on. When I push the button on the igniter, it makes a spark in the combustion chamber, igniting the hairspray. The quickly expanding gas created by the ignited hairspray pushes the projectile out the barrel at very high speeds. It is not nearly as powerful as my Pneumatic Rifle, but can still do plenty of damage. The boom/whoosh sound as the gun goes off adds a cool effect that is lacking in the comparatively quiet air rifle. I rigged it to attach to my blowgun as well. (it sends the darts through plywood) Because it is way more powerful than my blowgun by itself, it would be great for hunting small game, although I would need to built it differently to make it more accurate. PVC pipe is too flexible for very accurate shooting, and there is no place on this version to mount a scope or such.
This version is still plenty fun though!