Overlapping one UV over another

Ladies and gentlemen of the UE4 forum, I am once again asking for your support. I have here an HK416 I’ve modeled, textured, and shaded and it’s current material blueprint. What I would like to do next is make it have the appearance of being painted over its anodized aluminum finish by using some sort of a UV mask that I can overlay on top of this existing material which will still be visible where the paint has chipped off or was not applied. Does anybody know what that would look like in a BP?