Step 1: The parts
The parts I used on this gun are pvc pipes (rated at least 400 PSI!)Including the pvc drain trap and all reducers/splicers.
All of the brass fittings need to be npt(national pipe thread)I used 3/4".
As for the stock and the barrel, the came off an old pump action bb gun, but those were just to make it cooler.
The trigger is a blow gun, and the laser sight is optional.
The most important part of this is the VORTEC BLOCK, which itself takes some time to make.