If you do everything from scratch, you'll have to do it yourself. But look up the YT vid of the golden gun (an AR-10 made from spent ammo)
Granted, that guy shows off probably a million dollars in machinery but with enough care and practice you could build it all yourself, probably in less than a year of self-discipline, after which you'd have a program you could shove across the wires that could turn a solid block of metal into a mill-spec lower receiver. So long as lower parts kits and replacement uppers can still be you, you'll have yourself a gun.
There's a reason why guns are considered a god-given right, and not a man's-laws privilege. The gray matter between your ears plus a few square feet in the garage can get you pretty far in life.