It's about time to start getting quotes for some of these parts.
A word to the wise, the BATFE has been cracking down hardcore on the illegal manufacture of firearms. I'm not sure if a single prototype that is not for sale would be illegal, but I KNOW that a fully automatic weapon produced by anyone without a Class III NFA manufacturers permit is a BIG NO-NO.
I'm in the process of opening a firearms manufacturing business myself. Can't wait to see your finished product.