No Federal law prohibits you from building your own firearms.
AK receiver flats are easy to find, he just made his from a shovel.
If you build with the intent to sell you are required to obtain an 07FFL.
Need a FFL in Dallas/Plano/Allen/Frisco/McKinney ? Just EMAIL me. $20 transfers ($10 for CHL, active military,police,fire or schoolteachers)
Plano, Texas...........the Gun Nut Capitol of Gun Culture, USA https://www.youtube.com/watch?v=pELwCqz2JfE