Great, I can build a whole army of astromechs.

I also found a place online that sells 18 wood tubes, but those are around $75. 20 feet of PVC probably wouldn't be any less. I may go back to my origianl plan of building a frame from tubing and skinning it with aluminum sheet. It would be a lot more work, but I could do it for just the cost of the aluminum, I have plenty of scrap tubing available.
I saw a trash can in front of McDonalds today that looked to be about the right size, and it was a cylinder, not tapered. I may explore that option some more.
-S