Cut a 16 inch piece from the yardstick. This piece is the LOS and support arm. Then cut an 11 inch piece to form the crossbar. Cut two 3 inch pieces and one about 7 inches long. These pieces support the cross arm so should be adjusted to match the width of the yardstick.
Next step is to cut the moveable arm from the plexiglass.
This arm should be 19 inches long and shaped as shown in the figure. I cut a large rectangle using the score and snap method then used a craft saw to cut out the narrow portion. Drill a hole in the centerline of the plexiglass arm 2 inch from the wide end. This hole should be bigger than the bolt diameter to allow the arm to swing freely. If the support arm does not have a hole at one end then drill hole 2 inch from each end and along the centerline.