While it is legal to make your own firearms, they have to comply with state laws, even if you made one from scratch being that it is NOT preban (cuz it was made recently) it could not have any evil features, and in this state fully auto is illegal no matter what, doing what u described would just add a felony to the list of crimes (manufacturing AND possession of an automatic weapon) not sure what the EXACT charges would be but yea, short answer is definitely not, not in this state, not sure about in other states providing it gets ATF approval and all that good stuff.
Actually you can transfer a home made gun so long as it has a caliber stamped on it, along with a serial number or unique marking that can be used to identify it, and I'm sure there is some kind of safety regulation for that too. I don't know the details but I remember the subject of home made weapons being touched on in these forums.
27 CFR § 478.92 covers the requirements for marking a weapon that you intend to transfer to another (no difference in marking between 07 manufacturers and a home builder)
There is no specific number stated for a particular time period. The rule is you cannot sell more than the occasional homemade weapons with the intent to sell(cannot be a professional manufacturer without a license) . There is no specific cutoff that I know about. Its all to their discression.
