Those are beautiful and by the construction, the multi-welded pieces takes the hard work out of the equation. Mine were done using one piece of Aluminum and hand formed at every bend and elevation to conform to a stock fit. Remember that there are many grades of Aluminum hardness and softness. The right alloy has to be used to hold out, though in an accident, even the steel ones don't do so well.
If this mad science of weight loss was my life shift, I would have made every bracket available already. Lots of work that only can happen with passion. Now if only I can cook up a set of Aluminum doors for the early B's. LOL. AMD is asleep at the controls.