Individuals have been making their own firearms for the entire history of the United States and before. Homemade guns are not as popular as factory made guns, because factory made guns are easily and cheaply available in the United States. The Second Amendment has guaranteed that right.
It is a part of the right to keep and bear arms to be able to procure arms. A basic and fundamental way to procure arms is to make your own. Most home manufacture of firearms is for hobby or experimental purposes, although considerable homemade guns are produced in localities with extreme restrictions on the ownership of guns.
Delaware is in the process of passing a statute to make it illegal to make your own firearms, or to even possess a piece of metal that is intended to be used to make a receiver. From the proposed statute, HB 277: -- .....
"Nothing in the Second Amendment allows the government to create a registry of guns or to require them to be traced to the first retail sale. Such a thing is of virtually no use in solving crimes. Its sole purpose, it appears, is to pave the way for a registration system to facilitate confiscation."