You can actually get that case looking good. You can buy 1000 grit,1500 grit, 3000 grit, and 5000 grit sand paper at the Auto stores. Work your way through the grits with the CG removed then polish it with a Dremel felt wheel and polishing compound.
It is actually 400 grit I use on the CG. I miss typed in the prior post. With it removed make long strokes going one way.