Much is being made of the concept of using computers and plastic-3D printers to "print" firearms. Some see it as a bane on society while others see it as a great liberating concept, both for the same reason(s), i.e. that anyone can produce a firearm at any time so long as they have a printers. Something like the Star Trek replicators in concept, the printing of firearms is advancing quite rapidly. In as much as many modern firearms are mostly made of some sort of polymer anyway, there is little or no stigma attached to such a firearm. To put it another way, plastic guns made one way work, why not plastic guns made another way? Printing of guns might me that way, at least for the some gun smith.
Sor far as it goes now, it isn't illegal for an American to fabricate a firearm so long as it meets the other criteria as mentioned in the linked article. Handguns must have a rifled barrel to avoid being an National Firearms Act (NFA) regulated firearm and they must have some metal in them to avoid being an undetectable firearm. However, the real attraction of printing firearms comes from the ability to "stick to the man", i.e. the government, a concept that many currently active progressive/liberal politicians have supported from the time of Richard Nixon. Unfortunately for them, they are "the man" now and they are all too well aware of that. They don't like it one bit and they intend to make it illegal.
It might be interesting to watch this show. Unfortunately for the banners, history doesn't support the idea of successful bans. If you don't believe me, just look at all the marijuana these same folks smoked since the 1960s. If people want something, they'll get that something and use it as they please and eventually it will become the norm and permitted. This is happening with pot in Colorado, California and Washington, it is happening with homosexual "unions" and I'm sure it will happen with any number of things before I die.