Neilfj is right.
Here is the federal info:
From [url=http://www.atf.gov/pub/fire-explo_pub/qanda.htm] ATF Questions and Answers[/url]
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]
View Quote
Here is a link to the [url=http://www4.law.cornell.edu/uscode/18/pIch44.html] US Code (18 USC 921, et. al.[/url] from the above ATF quote.
You can check your state laws by calling your state district attorneys office and asking for the attorney in charge of firearms issues.
Cheers, Otto