This is a great thread. It inspired me to make the same repair on my car last weekend. I wasn't as diligent at taking every pic every step of the way, but I hope I have enough on here to share my version of this.
I had taken my bumper off anyway to repair my leaky headlights (will cover that in another thread) so I made my reinforcement with some thin aluminum strip. I used a propane torch to anneal the metal first, and the can of air duster held upside down to freeze spray the metal to cool it quickly. I was able to hammer it into shape and sanded the outside edge to match the contour of the bumper. I used a sharpie and the old piece to locate the hole, then drilled it out and filed it to shape. I used both 5 minute epoxy and rivets to secure it in place. I used washers on the back side of the rivets in the front of the bracket, too, to not rip through the plastic, and repeated this step for the other side. The final fit is good, but could be slightly better if I enlarge the snap fit holes more on the car itself. Maybe the next time I remove the bumper I can adjust it more.
