I’m about 48 hours into full Glowforge ownership (huzzah!!!) . My proofgrade materials have not yet arrived, so I am testing on some of my CNC scraps and supplies. I have some thin anodized aluminum business cards that engrave quite nicely (AMZN Link: http://a.co/cYSJya5). So, My GF now has a name badge:
Focus Depth: 0.04"