I HAVE FINISHED carving the exterior of all six backs. Shaping those rascals with a rasp means the removal of a lot of wood and lots of exercise for the arms and shoulders. I have also done the preliminary hollowing of the undersides on four. For that I use the drill press. When I have finished hollowing the final two there is still lots of finish work to do on them, but that will be with power tools. Dusty but easier.
The value of mass production is not very evident in this process, This is simply a one at a time slog with no advantage to doing six that I can see other than gaining a certain rasping expertise through repetition.