This is ED-209, my makerspace's(http://dhmn.net) automated sentry turret gun.
We're working on a redesign of the hardware, but in the meantime I'm using it to experiment with MRL.

I am using three servos, there is pan, tilt, and one to fire the trigger. The gun is a toy Airsoft pellet gun, but we also have an interchangeable paintball gun. There is a camera mounted on the gun, and there is a stationary camera mounted nearby.

The idea is for the turret to be completely autonomous, it should fire on anything it decides to be an "enemy". The motion detection script needs some work still, and the flickering florescent lights make ED-209 crazy with rage.