...welcome to the future. Neat stuff.
The next fronteer of 3d printing is with melting of powdered metal to make parts. NASA is already making rocket parts out of metal with 3d printers. So I would say that it will be possible at some point to print the entire weapon - perhaps ammo parts as well.He has it to where the lower receiver will last 600 rounds before breaking.
He keeps improving.
The magazine should last a long time, no stress on it.
You still need a steel barrel and the other parts.