I have a machined aluminum air cleaner(yes, it's billet) that I want to remove the shine on. What are some techniques that can be used? I'm thinking sandblasting, glassbeading or a chemical process to etch/oxidize. I'm wanting an appearance similar to old aluminum valve covers that have a darker oxidized look. Like most here, I don't like the billet look but some billet items might be used if they can be "disquised".