I'm looking to do some of my own cosmetic repair on an iPhone 5s and an iPad Air. I have attached photos to show the cosmetic damage in question. The iPhone mainly has these very tiny crater holes in the metal finish. The iPad only has this strange slight brown discoloration on one of the volume buttons. I'm hoping that perhaps some light sanding and polishing will fix this cosmetic damage? I just want to make sure that whatever actions I take isn't only going to result in more cosmetic damage. I'm not experienced with doing this sort of cosmetic repair to a metal finish. Constructive insight is much appreciated.