Getting a makerbot at work, therefore lots of questions anticipated!
Any clue which SE might be best?
Maybe Electrical Engineering, but I'm not sure. It'd probably depend on the question.
Updating Anna's answer:
Digital Fabrication had little success.
Still, it seems there is a constant need for such a place, because its successor, 3D Printing and Rapid Prototyping is currently in proposal stage.
I stumbled on this question searching for a similar place, and encourage all those who do to take a little time to back up this Area 51 proposal.