My problem is with the term and its use. Created and used by a few (at first), childishly immature individuals in order to taunt the govt by APPEARING to avoid "registration".
Now its been "recognized" by the anti gun people as a "huge problem" (which, it is not) and their potential solutions to the imaginary problem could end the legal ability to make a firearm (ANY firearm) for your self.
And I don't mean just assemble one from premade parts, either. Some go so far as to want to ban ownership of SPARE PARTS for guns you already have, because, you know, someone might make an unregistered gun out of them...
the law has been the same for generations, you may make a firearm, by and FOR YOURSELF, without it being required to be registered with the Fed Govt or needing a serial #,
as long as it is in your possession.
You cannot make the gun for sale, though you can sell the gun you made for yourself, if you get tired of it. HOWEVER, WHEN you go to sell it, THEN you MUST put a serial number on it, and it gets registered with the govt. AND, you become the manufacturer of record for that firearm.
If you don't, you're breaking the law.
Yammerheads on the internet doing the 21st century equivalent of sticking out their tongue and going 'neener neener" at govt regs and public perception created the issue, much to the dislike and disgust of the people who make their own guns as a hobby and don't brag or break the law doing it.
and anyone who would one day like to do it now has to worry that the law will be changed to prevent that.