Dunno if it qualifies as “sophisticated“ but original AK is designed to be made from like a piece of sheet metal and others pointed out you can rifle a barrel in your garage.
Only if you want to crank them out by the millions. As the "shovel AK" clearly demonstrates you can get it done more easily if you don't need to produce them at scale.
Vs buying an 80% blank, drilling a few holes, and then routing.