ummm thats BIG! Block makes one but its very expensive... look into Morrell target wall. its made up of blocks but is cheaper
i know a guy around here gets 16ftx16ftx12"deep styrafoam blocks from work. we cut them in 1/4s and shoot at them. maybe someone around where ur at makes them
stop Not exactly sure if this is what you are looking for. But if you want something that wide try your local sand and gravel company. Sometimes they have used coveyor belt. I guarantee you won't shoot threw it.
i just wanted to see if this worked?...........................it did! like to add it to the other smileys.