Already admitted that I am not good at free hand cutting the bevels on control surfaces. So instead I have been cutting off part of the foam board and replacing it with balsa. In this case I took a 3/16″x3/8″ strip and cut a 45° bevel on the table saw. So as shown below, the aileron is separate from the wing. Vertical and horizontal stabilizers work the same way. Then I use brown kraft tape to attach the pieces to one another for the control surface hinge.