3D printers are going to become more and more prominent as technology improves. They're already working on models that can print metal and (more interestingly, IMO) living cells/flesh.
Personally I can't wait for the day when there's a 3D printer in every home.
And that spinning thing doesn't have anywhere near the close tolerances needed in a working gun.
Mr. Kalashnikov might have some input about how well firearms can work when made without ultra close tolerances.