Most gun control laws, as currently written, are unconstitutional. The reason they have stood for so long is either challenges were not brought, or the supremes refused to hear the case.
Heller and Peruta affirmed the individual right to bear arms for the purposes of individual self-defense as well as group defense . It is legal to manufacture firearms for personal use (and always has been). Licensing and serialization are only required if you choose to manufacture arms for sale to others.
The bottom line is that manufacturing your own weapons is legal - as per the ATF FAQ:
9. May I lawfully make a firearm for my own personal use, provided it is not being made for
Firearms may be lawfully made by persons who do not hold a manufacturer’s license under the GCA
provided they are not for sale or distribution and the maker is not prohibited from receiving or
possessing firearms. However, a person is prohibited from assembling a non-sporting semiautomatic
rifle or shotgun from 10 or more imported parts, as set forth in regulations in 27 C.F.R. 478.39. In
addition, the making of an NFA firearm requires a tax payment and advance approval by ATF. An
application to make a machinegun will not be approved unless documentation is submitted showing
that the firearm is being made for the official use of a Federal, State, or local government agency (18
U.S.C. 922(o),(r); 26 U.S.C. 5822; 27 C.F.R. 478.39, 479.62, and 479.105).
Currently there is a very pro-gun trend throughout the country. I do not see lawmakers stomaching any more gun-control any time soon. Personally, I would like to see many of our unconstitutional gun-control laws repealed or struck down by the courts.