I like to use construction materials in unconventional ways. After all, just because a certain material was developed for a certain purpose does not mean it should not be used for something completely different. This is one of the games of the modern architect.
There must be a lot of sloppy painters in the world. So many, in fact, that industry has responded by supplying them with canvas tarps at strangely low prices. You cannot find canvas (no hem) at the fabric store for less than a small fortune, but painters tarps (ready to) go are $20 for 9 x 12. Crazy.
Sure enough, paired with a stick of electrical conduit and some shower curtain rings those painters tarps make a pretty good curtain.
There’s also this stuff called soffit board. A soffit is a lowered section of ceiling, and the board made for it is ¼” cement board. This is really brittle but otherwise stable stuff. I got the idea to use it for a shower surround. I stained it, sealed it, and shot two layers of it to the framing. Sanded caulk was used for the joints. I think it turned out pretty good and it was not expensive.