I made the mount for the eye iris servos. I machined this from a block of Aluminum using a milling attachment on my benchtop Taig lathe. It's attached to the forward servo plate using two 6-32 screws. The servos are a pair of Hitec HS-5085MG digital servos. Since the servos are required to turn in opposite directions using digital servos allows me to simply program the servo rotation direction without having to modify the servo. IN order to get the proper movement from the servos I installed longer heavy duty servo arms.