With all the curved pieces done this left just the side plates and uprights which can be made with more traditional woodworking techniques. The side plates are made from 3/4” plywood and become the mounting point for the side legs.
I started by cutting the pieces to size on a table saw. I also cut most of the long side of the notch on the table saw to get a straight cut and finished the cut on the band saw.
The only other cut that needs to be made on these parts is a slot to hold the shoulder wings. This slot was far enough from the end of the board to allow me to simply clamp on a piece of wood as a guide fence that the edge of the router plate could run along. This is simpler then trying to setup for a guide collar.
The plans show notches cut at the top and bottom of these parts that are used to help align the parts during assembly. For now I decided not to cut these.