This is not small business manufacturing but personal manufacturing. This technology is still in its infancy and many improvements are needed to enable parity with "the real thing", but feasibility has been proven. Any number of laws can be passed to attempt to prevent this of course, but these will be laws against information being exchanged, not goods. The point that by prohibiting the traditional retail distribution of arms is not going to cause arms ownership to shrink to political insignificance.
I know nothing about this “personal manufacturing” trend, and was only using zip-guns as an example because it was the first thing that popped into my mind. Z-guns of course were primarily used as inner-city gang-on-gang “equalizers”(going back to the 1940’s probably) and probably don’t have any bearing on any bleak scenario I can envision where “groups” representing one side or another, legal, quasi-legal, or “outlawed” might be arrayed against one another in some kind of apocalyptic ongoing “shoot-out”, resulting from the 2nd Amendment guarantees of self-defense.But I can see how you say that laws against this will probably be against the “information” being exchanged and not the guns themselves.
That would involve an unusual political bedfellowing of the Government, and any or all gun manufacturers. Unprecedented but I could see it happening, in “intellectual property” terms. Just beware of guns coming in from China, reverse-engineered sloppily, with bullets that wind up exploding in the barrel. (”Whoops! Our mistake! Sorry!)