"Repeal the second amendment. Failing that, use a highlighter on the words "well regulated militia" to help SCOTUS find them."
Doable in the era of CGA; the highlighter, of course; 2A is here. There are more weapons than voting age citizens to do this.

"Nationalize companies that manufacture firearms and shutter them" ... not happening:they fucking ARE the MIC.

"Institute a law modeled on the Japanese Firearm and Sword Possession Control Law. Confiscate privately owned firearm" Ok... there are almost more firearms than citizens in this land of the free, so you would need increased army of cops... in a society that is going more fascist every day. Real good...

"Define the NRA as an organization that provides material support to terrorists. Disband it" And they are on the honor system to return the hardware... real good...

"Remove and make permanently ineligible any office holder who has ever accepted a campaign contributions from the NRA" Riiiiight... A politician who will vote to eliminate his sugar daddy? The Onion wouldn't propose that.

"Find the knuckle-draggers who insist that we can have their guns when we pry them from their cold, dead fingers. Accommodate them" I have a .22 rifle I was given when I was a kid (5 yo). I haven't fired it for maybe 30 years, but every new year, I clean and oil it. You can't have it. There is a finite chance I may have other firearms I have collected over the years. Uuummmm.... you can't have those either, assuming, of course I had them. The second amendment isn't the whole of the constitution.

Pretty thought though...