Split a piece of 6" sch. 40 pipe use half for the top. 1/4 plate on everything else. 3" pipe post with two feet concreted in the ground. This will take care of the damage. Made one for myself, and several for relatives and friends.
About a week after I put mine up found a warped aluminum baseball bat in the ditch behind the box. Just scratched the paint. I asked a lady at the local post office prior to building. She said you can make a box of whatever you wish.