Sen. Blumenthal (D-CT) has, once again, introduced legislation to regulate so-called "ghost guns." Additionally, Rep. David Cicilline (D-RI) introduced similar legislation in the U.S. House. Sen. Blumenthal has named these bills the Untraceable Firearms Act (H.R.3088/S.1558)
"Parts kits" consist of everything but the frame or receiver, which is the only part regulated as a firearm. Americans buy parts kits for a host of lawful reasons, including for spare parts, historical value, and to home-build a new firearm. Indeed, making firearms at home is an American tradition that predates the United States. Further, this would fundamentally outlaw many forms of 3D printing. All state and federal firearms laws still apply, even if someone builds their own firearms at home. This is simply smoke and mirrors targeting your rights and property.
Technology changes, rights do not. Americans have a long tradition of home-built firearms from even before we were a country.