Not sure… you figure the average (standard anyway) ceiling height is 8 feet, take away 12 inches from that (the clamp mechanism takes that up) and you’d have to ask yourself how rigid is a piece of PVC (even furniture grade) at 7 feet long?

Since the strength (what’s holding everything up) of this shelf is in the rigidity of the pipe and how tight it is clamped between the ceiling and the floor, compounded by the length of PVC you’d have to use I’m not sure it would be rigid enough; I picture the PVC bowing out as you clamp it down. But maybe if you used 2 inch or larger diameter PVC it may work. It certainly would not hold as much. You’d also have to substitute PVC fittings for the metal – Kee Klamp – ones I used to hold up the shelf as they would not work out so well; I’d imagine the set screw would crack the PVC.

It’s not that odd of a question though – some people brought it up on instructables as well. If anyone does make this shelf with PVC I’d love to hear about it!