Has anyone engraved a Lower/Upper Receiver?

[Whelenon]

I would laser engrave the uppers to Cal specific, assuming all your uppers are complete units. I've talked to a local Trophy Shop who does laser engraving, he could engrave an upper on the flat just below the picatinny rail without a problem. Just like AA does with their receivers. The upper is alum so it's not going to rust. There are also ways to paint the lettering if you don't want to leave it silver.