[bgill]

So, no serial numbers or registration?

[MrB]

I’m sure there are laws against “manufacturing” without a “license”.

For instance, you can get into some big trouble with the ATF for possessing a threaded tube and some steel wool.

[theBuckwheat]

Registration is a state or local issue. In many states you can make and possess a firearm without any government involvement whatsoever.

[SledgeCS]

Only the AR-15 lower has a serial number on it and that is what needs to be registered. You can currently buy non-serialized AR-15 lowers, which are perfectly legal. They are referred to as “unfinished ar 15 lowers”, a google search on phrase will return a lot of hits. They can legally be sold without a serial number because you need to finish the lower yourself. You can do so with a drill press and the jig the companies also sell.