I went to a gun show this past weekend and saw where a guy was selling 80% receivers, which are by definition from the ATF, a paperweight. The remaining 20% of the machining can legally be completed by the end user and you will have a non-serialized, no paper trail lower. Seems intriguing, but is certainly not the most affordable route to go. The 80% blank costs just shy of a fully milled and legal (read: sellable) lower receiver plus you had to buy a jig (~$150) plus a drill bit kit (~$45). You'd have about $250 in a "ghost" receiver vs $60 plus background check in a fully transferable receiver.
I came home an did some research and it appears that you can get polymer lowers with a disposable polymer jig for <$100, but you'd still need bits. Some jigs are cheaper but require a drill press to mill everything out.
Has anyone done anything like this before? Pros or cons?http://www.80percentarms.comhttps://www.youtube.com/watch?v=SiHdV5slQps