You are doing a great job of randomizing the surface like real aluminum would respond. I don't know how you get the metallic look to come up out of the current oxidized aluminum look but, when you do, your patterns are Da Bomb.... 
Thanks, man. If I could skin as well as you make maps we would really be getting somewhere.
It's a combination of grays and light blues randomized and blurred. These are carried over to the spec maps. I will post some examples once I finalize the skin to everyone's liking. I learned a lot from the original (this is an adopted skin) and used what I saw to make my own metal effects. I still don't fully grasp how people do it from scratch via filter tools. My method (cut, paste, spray paint, darken, lighten, blur) definitely is more time consuming than theirs I bet.
