you can follow simple instructions and "finish" an 80% finished frame. Ares Armor is one place that sells these frames. the rest of the parts are legally bought thru the mail by anyone. Only the frames are serial numbered "controled".
I can buy guns face to face using the internet or newspaper ads without paperwork in TX. Nice to know about the unfinished receivers though.
Yea, you can finish the lower receiver if you know what you're doing and also need speciality tools. Typically a person who knows what they are doing, already knows about the ability to purchase an unfinished frame. So, I'm guessing the reason for the OP is to create panic about scary unlicensed guns?
millions of "gun guys" are unaware of the 80% "wrinkle" If your idea of "specialty tools" is a $60 bench mounted drill press from Harbor Freight Tools, I guess you got me on that one.