What she made meets the definition of a 'Firearm' under the NFA
26 USC Chapter 53 § 5845(a)
Firearm. The term 'firearm' means...(4) a weapon made from a rifle if such weapon as modified has an overall
length of less than 26 inches or a barrel or barrels of less than 16 inches in length;...
She 'made' it:
26 USC Chapter 53 § 5845(i)
Make. The term 'make', and the various derivatives of such word, shall include manufacturing
(other than by one qualified to engage in such business under this chapter), putting together, altering,
any combination of these, or otherwise producing a firearm.
Doing so is a prohibited act:
26 USC Chapter 53 § 5861
It shall be unlawful for any person ...
(f) to make a firearm in violation of the provisions of this chapter;...
Which leads to:
26 USC Chapter 53 § 5871
Any person who violates or fails to comply with any provision of this chapter shall, upon conviction,
be fined not more than $10,000, or be imprisoned not more than ten years, or both.
Which, gentlemen, when combined with the video of our Wannabe Congresscritter, is prima facie evidence of a felony-level violation of black-letter federal law. Note there is NO discussion in the statute of intent, reasons, follow-on actions, etc. That she did any of it for 'politically permissible reasons' is irrelevant. If any of us had made the same video (minus the anti-gun rant) and titled it "How to make a SBR", we'd already be under the jail. Somebody needs to wake up AG Naps-a-lot and get him to sic the dogs on her.
ETA: That the aforementioned 26USC chapter is blatantly unconstitutional is a legitimate defense, as we'd all likely argue. But likely not a route she'd like to go down, as it'd mean I'd be able to purchase a Thompson at a reasonable cost, without all the associated taxes, registration, and bullshit oversight. Just sayin.