[Inyo-Mono]

“Among the executive actions under consideration by the administration is one that would require buyers of so-called ghost guns — homemade or makeshift firearms that lack serial numbers — to undergo background checks,”

That already is a law. If you built a so called ghost gun (perfectly legal) you have to go through an FFL dealer to sell it.

[Scrambler Bob]

That already is a law. If you built a so called ghost gun (perfectly legal) you have to go through an FFL dealer to sell it.
= = =

After you go through a procedure to get a serial number, and have been registered as a gun manufacturer.