I got tired of having to open the door before leaving for work and going out in the dark to close it. Sometimes I wouldn't get home till late and would worry that predators may enter the coop. So I searched the net and made this screw drive mechanism and it wasn't even that hard really. The parts I used were : Plastic enclosure ( but a home made plywood box would work ) Old 18 volt cordless drill 3/8 All thread 2 1/2 ft long 3/8 nuts Two 120vac double pole ice cube relays two normally closed limit switches 6 volt battery out of an old UPS for a computer. battery trickle charger Old lid off plastic storage box 120vac Lamp timer ( although I may switch to a photo cell ) I will make another one and probably use a smaller enclosure, use cord strain reliefs, have a better layout and better materials for a door. I just wanted to use what I had and get it done before the rain. And hey it works!