nonstoprc, after you build the ply plate assembly to fit the area I described above, you need to scribe a centerline and a vertical line with a pen on the stab in the location you've chosen. It is very important to make these lines on the foam as accurately as you can and then scribe around the ply plate. Again, for building accuracy, these lines and locations need to mirror each other. Then remove the foam INSIDE the area you scribed for the ply assmbly with an exacto blade down to a depth that will accommodate the ply plate with the stab adjuster attached. Take your time as you remove the foam carefully and test-fit the ply plate assembly as you go. You will know when you have the right depth. It really helps if the opening in the foam provides a snug fit for the ply plate assembly. In retrospect, I probably should have started my first response with scribing the lines on the foam. Oh well, I hope this helps you and others that are willing to build their own planes. Regards again, Everette