As long as it is not fully automatic, if you can find a way to build your own ak47 rifle it's completely legal. If you plan on selling it it must be serialized, but if you just want to make you're own it doesnt have to be. You can legally make a gun in the US as long as it meets federal and state laws.
How much does it cost to build your own AK?
Builder of custom firearms. In the USA at least it was costing us around $550-$650 in 2018 just for the parts to build a high quality AKM. The largest cost was the old demilled parts kits. They started at $300 and went up from there depending on country of origin.
Are AK parts kits legal?
Although US customs laws ban importing the weapons, parts kits—which include most original components of a Kalashnikov variant—are legal.23 may 2013
Are all AK-47 parts interchangeable?
Many of the countries that make AKs do so under contract with access to Russian specs. But also, many others do not and may have reverse-engineered their AKs. Because of this, most parts should be interchangeable — but not always, as it depends on the source of the parts.4 sept 2015