Even though there are already two other versions of this exact Thing on Thingiverse (and one on Shapeways), mine worked so well I felt I should share it.
BTW, I got this keyboard for free, because whoever lost the original leg threw it away! I'm no tree-hugging, whale-loving, bubble-blowing jelly-fisher, but that's just wrong... Find out who your local dumpster-diver/scavenger is and give him/her your unwanted electronics!
I printed this in PLA, since that's what was in my printer :P
I don't really remember my settings (other than that I didn't use a raft), but they wouldn't help anyone not using a Micro, and they're probably not critical, in any case.
Making it Non-slip
I added a bit of clear silicone to the little inset in the end to prevent the keyboard sliding around the table. Sugru, Oogoo, or Hot-glue might also work.