A reply from Tony Sinnett has enlightened me to how carving may be approached differently in the industry. In an earlier post I showed a clay sculpt of Bing Crosby. Appently this model is used as reference to ruffly shape out the head in wood using a copy carver.
The below video shows how it works. The operator holds a stylus onto a master copy of what they want carved in this case a bass guitar body and moves it around the form of the object.
The stylus is connected to an arm with a router on the end that moves in the same direction as the user. Following the master forms shape with the stylus the material on the bed next to it is cut in exactly the same shape. Its basically a human controlled CNC machine and you can even buy a similar attachment to go on your normal hand held rounters.
From what Tony explained to me this must be how some marionette makers can produce such accurate recreations of heads in wood and also mass produce puppets parts on a small scale.