Cut aluminum angle for bracket that goes under the layout to hold the servo and arm to control a semaphores. As shown I use the cheaper 'Steel Blue' by Sharpie to mark locations for drilling and milling. It does work just long enough to get the job done.
Using the height gauge to mark lines to locate holes and cutouts. (The marks are there, just hard to see.)
Then center drill and drill the 12 holes.
The final step is to mill and then file the corners of the notches for the servos.
The bracket is shown upside down (sorry). Three of the four holes along the top edge of the bracket (bottom of photo) will be used to screw the bracket to the underside of the layout. One of the two holes on the other end will be used to mount the small circuit board to provide power for the semaphore LEDs.
The two holes near the center of each side is where the arm is mounted.