clawfoot tub shower enclosures too expensive
In college, I made a simple hanging shower enclosure for an old clawfoot tub in our fraternity house with 1/2" galvanized pipes with 90s at the corners hanging from the ceiling by small chains (it was rectangular by choice). I overlapped three plastic shower curtains for the walls. I plumbed in a galvanized pipe and shower head with separate valves from the tub faucet, and you can rig anything to hang the handheld from the hanging shower curtain ring.
Have you thought about trying to find a kids plastic hula hoop? Or you could make your own thing with white plastic PVC pipe and fittings in any size that suits you, although it wouldn't be exactly round....perhaps just a small square or octagon.
You're only talking a fewbucks with this arrangement that would get you to what you want I think.