You mean like how Smith Machine Group has already been making the FG42? They did exactly that......recreated the gun from scratch, part by part. Except for the magazine
Obviously that's coming at a cost, however, as they're essentially one off builds out of a very small shop. I'm curious if there's been any attempt by SMG to sell their plans, or larger established manufacturer to buy it. If you could get a larger manufacturer to produce FG42s for $2k, they'd sell like crazy. Without question, even more so the Stg44...they wouldn't be able to keep them in stock. Maybe not as much the Fedorov or RSC-1917, but the M1941 Johnson would likely do well as well with the same crowd that collects M1 Garands and M1 Carbines.