I draw from a cardboard cutout, as scalecraft does, to get the shape. I use a dremel reinforced fiber cut-off wheel to rough cut it, then rough shape it with a rotay carbide bit in my dremel. I clean it up with a fine round rat-tail file. Be sure to leave a radius at the back side high point of the cut-out (on the vertical side). I have seen several squared off here, and they will crack out and fail.

Jeff