You know what’s even faster and cheaper than building a 3d printing gun factory?
Just buying a bunch of lower receivers. There are plenty available for less than $50. Hell, there are companies that sell them in 3 packs. If you are trying to build an arsenal you can just go to a gun store, there’s no limit on how many you can buy at once. If you don’t want the purchase to be background checked go to one of the many states that allow unrestricted private gun sales and go nuts.
the crux of fear is that "the enemy" may enter the country, hunkerdown, and anonymously construct the chattels of an assault.
in that threat model, appearances on camera buying anything related to a "mission" are going to be avoided.
no one, not even an FFL will see your face, if its all made from scratch.
this fear of takeover by a "hostile aliens" is quite alive, despite the promises of the GunControlAct