I too was thinking anodized aluminum. You are good people JBAnodized 040 aluminum with diamond drag lettering. Relatively cheap and super simple. I've done these in the past when a family couldn't afford a tombstone. I felt bad and sold it under our minimum, but still came out in the black.
Pete, do you make those or where do you source yours?also look in to metal photo nameplates. that's how we do all our military nameplates. extremely durable