"In October 2014 Wilson revealed his biggest project to date: the Ghost Gunner, a miniaturized CNC milling machine small enough to sit on a desktop. It’s thousands of dollars cheaper than big CNC mills—computer-programmable industrial tools for cutting away material—and capable of producing aluminum lower receivers compatible with the AR-15 rifle."
If I wanted to make my own lower, and those Ghost Gunners were being sold and shipped today, I'd personally still go the traditional 80% route.
The real part of all of this that makes me unconcerned is that these things are really only interesting for somebody who is intent on staying within the bounds of the law. If you don't care about the law, fucking around with all of this home manufacture stuff doesn't make much sense. Just find a non-felon criminally minded buddy to purchase a complete gun for you (or just do it yourself if you are not a felon). If you live in a country where that isn't possible, will it really be feasible to get the rest of the parts after you've milled your lower? Does the UK allow you to purchase all non-lower receiver parts of an AR-15? Would they allow you to receive the specialized mill in the mail in the first place? I honestly don't know.
For the 3d printed lowers: drilling out your own 80% lower will give you a superior result with far less equipment.
For the 3d printed "Liberators": a quick trip to your local Home Depot's plumbing and hardware departments will let you throw together a shotgun, not a dinky little pistol, that probably won't blow up in your hand (still possible if you choose the wrong pipe I suppose, but compared to the plastic gun?....) There are videos on youtube of teenagers in the Appalachians doing exactly this just for the hell of it. It doesn't require any real manufacturing skill.
What Cody Wilson has done is realize the political potential of 3d printing. It's not a very good way to make a gun, but it seems to be an excellent way to get people talking about making guns.