Not a federal crime for some values of "manufacturing": http://www.atf.gov/firearms/faq/firearms-technology.html#commercial-parts-assembly http://www.atf.gov/f

Not a federal crime for some values of "manufacturing": http://www.atf.gov/firearms/faq/firearms-technology.html#commercial-parts-assembly http://www.atf.gov/firearms/faq/firearms-technology.html#com... "Individuals manufacturing sporting-type firearms for their own use need not hold Federal Firearms Licenses (FFLs)." So you could manufacture an AK receiver but you would have to outfit with a Saiga parts set to avoid falling afoul of 922(r) restrictions on "assault weapons". I was only speaking to the U.S. as that is the only system I begin to understand the legalities of (and that would remotely allow this). The reality of an insurgency using 3D-printing to manufacture whole firearms isn't possible yet due to the stresses involved. I've had multiple mechanical failures due to MIM parts (metal injection molding) shattering in handguns. I can't imagine the current or near future 3D printing materials being able to surpass MIM in strength. It would be more likely to be used to make difficult to manufacture components for weapons, such as molds for shaped charges.