I made pvc gyms from just plain pvc you buy at Home Depot or Lowes. It comes in 8' tubes or whatever and whatever thickness you want. I use 1" thick stuff for my Allison my jungle carpet. My advice is buy the cutting tool too. It will make life easier as it doesn't leave the little burrs like a hacksaw will.

Anyways plan out what you want on paper, then cut it to the sizes you need, buy the fittings you need and stuff. I then roughed it up with some fine grit sandpaper. I didn't glue mine together as I want to be able to take it apart give it good cleanings when needed. You can also scorch the pvc with a propane torch outside so you don't breath the fumes and give the pvc a wood texture and coloring. Check out You tube or also check out the GTP sites. A lot of the guys there use them and make some pretty fancy looking stuff out of it.