I still think the point of the Liberator being all plastic was more for show, to demonstrate that you could make an entire gun just from the 3D printer. If, or rather when, this gets picked up by other developers who start tweaking it, I wouldn't be surprised if a "useful" mass production version of it will be full of easy to find store-bought parts. I'm still curious how much more effective and safe this gun would be if the barrel was designed to hold and reinforce a hollow, cheap aluminum rod, for instance.
Terribly unsafe, since AL (1) softens when heated above a couple hundred F and loses most of it's strength (2) work hardens when repeatedly stressed. So the end of the barrel which got the heat, softened, and the end that got the stress, split apart.
Like I said, the way this should work can be understood as follows. Suppose you own a shooting range in a locality that allows such things. Someone walks in and wants to shoot one of these things. What do you do?
The problem with this scenario, of the plastic gun is simply that there may be a legitimate public safety concern over it's production. By contrast, I mentioned the Anti_Al_Gore 3d printed showerhead. That is obviously contrary to the federal law governing max flow from a shower, but it isn't going to maim or kill anyone.
Keep in mind that other 3d printers certainly do print in metal, many types of metal. Those are more expensive units and will likely not be in everybody's garage. But that's no different than computer printers. There has always been a market for home printers, a separate market for business printers and service bureaus which handle the specialized jobs for anyone who needs them done.
