I keep going back and forth on what motor to use for my coop door. I have an antenna but don't like the idea that it needs constant power to stay open. I will be running everything off of a battery and want to use as little power as possible. I have also considered an automatic car window mechanism. I am not an electrical genius so the wiring of these things intimidates me a bit. I am sure if I knew how to wire it I could use a 12v cordless drill as the motor. Plug and play would be a huge plus for me. I love the simplicity of the Add-a-Motor D20 but read a lot of reviews about the plastic gears breaking. I am trying to get a sense of how common this is. The whole point of installing an automated door is so when I am away for the weekend the girls can still get out. But if it is likely to fail while I am gone it defeats the whole point. What is the general consensus here? Is there an alternative motor with metal gears? How reliable is the D20?