Thanks!
I used a U-profile, 3mm thick. It wasn't tall enough, so I had to use some angle-bar at the bottom of the bumper.
I bent the corners, welded tubing. I don't have a tube-bender that would bend thubing this thick, so for the center one I used bends that they sell. The corner ones I had from somewhere, I just used what I had. I think the corner ones should be a little thicker though.
I also used sheet metal to cover the underneath of the bumper.
After some body filler, I sprayed it with primer and then black from spray cans.
Right now I'm working on a bumper for my friend who has a Ssangyong Musso.