I polished a heat shield for my engine bay to a mirror finish. Do to the size of the aluminum, it took me 14 houres of polishing with an air gun, and Autosolve to get the piece mirror perfect on one side. Then proceeded to drill the mounting screws in the incorrect location. One 4 by 8 foot piece of ALUMINUM where I live in Canada, mill finish, costs me 400 dollars. A very costly mistake.
