Im sure there will be others but will have to be water proof or have a laquer top coat of sorts as it'll need cleaning. Spray paint is easy to find and not too expensive really- especially if you make a few hides!
If you buy exo terra hides I would suggest small for cave too as snakes feel more secure in a "tight" spot i.e. body contact with all the inside. I have a long corn at 5 foot 6 thats on weaner rats and she fits in a large one of those! The cave raises up from the floor so she's more like a snail when she's in it mind you but she won't use the X large one I got her while ago!