12yo DS wants to bounce his volleyball off his (white) bedroom walls and occasionally the ceiling. He has plenty of opportunities to play outside, so one option is just to say "no balls inside" but I'm considering buying something to put up on the wall for him to use as a safe target. It would need to be solid enough to give a good bounce. I googled and found some very heavy duty "wall ball" targets with a high price tag, but they seemed to be aimed at adults in gyms rather than kids' bedrooms. I was imagining something more like a noticeboard, but solid enough to take a ball, and giving a good rebound.
The best thing I've found so far is a wall transfer in the style of a target, which will at least limit any damage to one area, but it's a bit more permanent than I'd like - it would be nice to think I could just put something up temporarily until he's grown out of it, without having to redecorate.
Any ideas?