The problem is it's not realistic to machine a part like that in volume. There's just to much time involved. No one would pay what it would cost to make Is my dilemma. I'm open to a good universal design that can be made easily
If it could be made easily, we would not be so interested in your brother-in-law's capabilities!
I will likely be making my replacement out of a piece of aluminum bar stock (easy to machine) with mostly a drill press, hack saw, and thread tap. Probably will not have the double chisel bit file adaptor, which would be easiest on a lathe.