>It is not legal to manufacture firearms unless you are licensed.

This is false. It is legal for non-prohibited persons to manufacture non-NFA firearms without a license, provided you do not do so "for sale or distribution." Your state may impose additional restrictions.

(I believe it is also legal for non-licensed individuals to manufacture non-machinegun NFA items by filing a form 1 and paying the tax, but don't quote me on that.)

http://www.atf.gov/firearms/faq/firearms-technology.html#com...