But that just says that it is legal according to the BATFE - you can't use a tool to manufacture firearms unlicensed (or in this grey area, to complete someone'

But that just says that it is legal according to the BATFE - you can't use a tool to manufacture firearms unlicensed (or in this grey area, to complete someone's 80% receiver for them). That's a legitimate interpretation of an existing law - they're just saying you can't set up a service to finish up lowers for people - they define that as manufacturing. They'd change their tune if the smith was licensed to manufacture and added serial numbers. I'm unaware of anything that regulates machinery used to make guns, which until about a year ago, was general purpose machine tools (and still is for practical purposes - these Ghostgunner things are political art, not machine tools). I think people WANT to be able to say "that's illegal, or it might be". But it's just not. Not yet. (as far as I know, I can be convinced if someone shows me a law). I won't argue that the BATFE hasn't done illegal things in the past, and probably will in the future, but as far as I can tell, this is pretty black and white.