You publicly state, "I don't shoot much anymore", so you're not really building for your own use. You just enjoy building, but then wish to sell so you don't have too many. You are entering a 'gray' area in the regs/law. Much is about 'intent'. You intend to profit from making these and then selling? There is nothing in the regs that states "how many "before you need to be licensed. Just keep in mind, if some young 'hot shot' ATF Special Agent could bring charges, and make 'um stick (although you would probably be officially advised to 'cease and desist'), violations are felonies which would preclude you from ever legally owning a firearm again, and it'd probably cost you your job at Pierce. I think if you'd ask ATF this question, instead of asking the interdnet, they'd suggest you need to be licensed. With the current political climate being what it is, why try to 'push the limits'?