This reminds me, I have something I want to see if you can make for me (and I'm sure others would be interested). I want a real thin piece of metal that can go on the bottom of the door panels all the way accross to cover up the screw holes. I want to take the pressure of those screws off of that crappy plastic so I don't have to worry about them breaking.
I'll talk more about this later, back on topic. I vote that it is definitely something cosmetic because of how shiny it is, but beyond that I haven't got a clue.