It looks like a Plastikov uses a lot of metal Kalashnikov parts that you'd need to get from a kit or machine yourself or something, so I don't think it's really fair to call that gun a 3D printed gun. It uses printed parts, but the barrel, trigger, etc... aren't printed.
That's the entire point. The only federally regulated part that requires a background check is the receiver, which can be made on entry level printers by virtually anyone that can read.
