Just look up 3D printing technology. Think about a ink-jet printer that prints out something 3D with ABS plastic. So, with such a thing you could "print" out a gun. The technology is in its infancy, and although there was a guy who got a 3D printed AR receiver to fire a couple of rounds before it all fell apart; it's really not viable for the firearms industry at this time. But the technology will grow; who knows. In 15 years we may be sitting around listening to everyone bitch about the quality of 3D printed parts, longing for the days of MIM.