[Baz]

Instead of sandblasting you could just spray some of that rust reformer product or Ospho on it and then paint with cold galv spray. I like the idea of the wood bottom. 1/2" plywood would probably do. You do want the fasteners to not protrude up top, however you decide on that part. So a flat shovel doesn't have anything to stop it as you shovel out topsoil, compost, or mulch.