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:
Settings:
Speed: 200
Power: 100%
Passes: 1
LPI: 450
Focus Depth: 0.04"
Fun, right?
If I may… I’ve found I’m be able to get away with much faster speed with anodized aluminum. I typically use 1000/100/340. Pardon the expression, but I get laser-sharp results with those settings. Of course, your material may be different from mine, but, hey… if you can get the same results faster, why not, eh? 
Hope that helps you out!
Great job on it! (And very cool name for your Glowie!) 
Awesome! Thanks for the feedback!
Llamas make me think of Winamp.
I bought some of those last week. The coating is laquer based, not anodized. Similar result, but the settings would likely be different.
Same here.
