There are 2 3D printers outside my office right now,...and coupled with a scanner they are a mind boggling piece of equipment but only if you want a plastic or composite stock,...unfortunately ( or fortunately) we like to have our stocks made out of nice wood, and that would require a pretty sophisticated 3 axis cnc with tool changer, and even that would not come close to replicating the subtleties required to feel your way through the cut on a 3K piece of walnut as a good hand guided duplicator can.
Joe Cole of Cole's gunsmithing was doing something similar,...I was told by the lady there he is back to doing it by hand, took too long the other way she said
Best
CJ
