I have been looking at the heavy rubber horse stall mats to use in a boolit trap. I wish I had the money for heavy steel to build a trap but I'll find a way to make due. My Idea is to build a trap out of plywood. A box 4' wide about 3' high and four layers thick with a heavy rubber horse stall mat on the inside. I would make the back wall between 45 to 35 degrees to deflect into a sand pit. Now I would only be shooting slow lead nothing jacketed or riffle. Anybody have any thoughts or advice.