The bad news is that one of the common mistakes people make when gluing PVC pipe is assuming it can be undone later. If the joint was glued properly, that's unlikely. It's all about the adhesive.

PVC pipe is a valuable material to the backyard ... The possibilities could be further expanded by combining with these PVC fittings designed just for building stuff.

[NightHawkInLight] a.k.a. [Ben] recently built an awesome high power air cannon out of PVC pipe. PVC air cannons are great, and everyone should build one of these at some point in their life ...