[Philip W.]

My guess is that if you do a contour, you have to make a breakthorough cut and go through a piece of wood or something that the aluminum is mounted to. Mounting the aluminum requires so much effort, especially for all those wheels, when you can just do what's done in the picture and then flip the pieces upside down and face it all off.

I'm no expert machinist; I started learning how to use CNC a week ago. Correct me if I'm wrong, please.