Bubble wrap!! It may be annoying but it is not destructive and is soothing.

Take all the elements you say he gravitates to and build a mini sensory center.b in the "GO TO spot.. a wall with a grill and find a large log and have somebody slice off a piece of that. he for sure is sensory seeking..I believe it is the vibrations of that, and the energy out put that are soothing to him .You can even put velcrow dots up on that wall board and add sight words weekly to it, he is already there at the wall might as well make it fun have him tap out the word, put music to it. this way you have two things going he has his sensory diet meet and he is learning sight words too.. just another idea

Its bad because he has messed the walls up, but he likes to bang on metal surfaces like the grill or our fireplace he also likes the tree trunks.

Re direct him -TO his designated "Go TO spot " say you can not do that on the kitchen walls or the bed room walls but you can drum in your room--Think about the difference in vibration and contact you get from a wall this is totally different from a drum, those surfaces are total different and he finds that wall drumming gives more a vibration and impact it most likely helps his muscles too.. so I suggest you get a few boards that are Wall like, from the home depot place. frame out the extra wall board and screw it on his GO TO SPOT in a designated area, in his own space or room, this allows 2 thing to happen. first he has his GO TO sensory tool. he wins and you win.. and you have a preserved wall.

Thanks will try it.