In the US we can build our own guns for personal and folks do it all the time. It makes for wonderful Youtube entertainment. There are certain restrictions and machine guns generally are not allowed. However we cannot discharge firearms at the bedroom walls. That's pushing the envelope even in the US.
From the Bureau of Alcohol, Tobacco and Firearms (ATF) FAQ pagehttp://www.atf.gov/firearms/faq/index.htm
A7) Does the GCA prohibit anyone from making a handgun, shotgun or rifle?
With certain exceptions a firearm may be made by a nonlicensee provided it is not for sale and the maker is not prohibited from possessing firearms.
However, a person is prohibited from making a semiautomatic assault weapon or assembling a nonsporting semiautomatic rifle or nonsporting shotgun from imported parts. In addition, the making of an NFA firearm requires a tax payment and 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 a federal or state agency.
[18 U. S. C. 922 (o), (r), (v), and 923, 27 CFR 178.39, 178.40, 178.41 and 179.105]
The faster I go, the older I get.
"I am with you Flintsy ." SidebySide
Flintlok, I think you're dead right....."The Dogge"
" when an American comes on the forum .....and then gets a bit upperty ..."