Now that both ears are on the headset, it’s time to adjust the right ear’s position.
Put the headset on and look in the mirror. You want the ears to be symmetrical. If they aren’t mark the headset with a pencil where the edge of the right ear servo mount should be.
Then take the ears off and loosen the mount, slide it into place, and tighten again. Repeat as necessary.
Put the ears on the styrofoam head and zip-tie the cables together, and run them back to the rear of the headset, as shown.
Attach servo extension cables to the ear servos.
Remember to label the servo extension cables, too: left pan, left tilt, right pan, right tilt.
Success! You should have a pair of ears on a foam head, with servo extension cables running away, ready to be controlled by an arduino.
(Optional) This is an excellent time to start making fur or fabric covers for the ears, now that they’re on the headset.