Step 2: Construction
The construction of the launch apparatus (see below for a diagram) is as follows.
Attach 22-inch-long pipe to the 1½-inch male pipe thread adapter using PVC cement.
Attach 1½-inch female adapter to 1½-inch to 3/4-inch reducing bushing using PVC cement and allow to cure.
Screw male pipe thread adapter assembly to female pipe thread adapter assembly carefully.
Drill hole in one 3-inch end cap the diameter of the tire valve. Insert the tire valve into the cap.
Attach both 3-inch end caps to 3-inch diameter pipe with PVC cement.
Use solvent weld to attach the 3-inch pipes to the tee connector.
Take the second reducing bushing and attach the 1½-inch opening to the tee connector with PVC cement.
Wrap the heads of the 3/4-inc pipe nipples using Teflon pipe tape.
Insert the nipples into the ball valve (or as it has been suggested the pneumatically modded sprinkler valve).
Screw the ball valve-pipe nipple into the 22-inch barrel.
Screw the new barrel assembly into the pressure chamber.
Allow to cure overnight.
Wrap the pressure reservoir with three layers of duct tape. (optional)