Anybody ever used one of these? http://www.petsmart.com/product/index.jsp?productId=3510043 I have gotten tired of my chickens making lots of noise wanting to get out of the coop in the mornings. I'm thinking of building a new coop that is smaller. As a side note, the 4 sq/ft rule per chicken in a coop is ridiculous IF you live in a mild climate where your chickens don't spend any time in the coop other than to sleep or lay. Anyways, without the expense or bulk of an automatic door, I want a door that will let the chickens LEAVE the coop in the morning but won't let any critters IN the coop at night. These four way locking pet doors seem like they would work because you could set it to "out only" at night when the chickens are in the coop, and then in the morning after they have all exited the coop you could set it back to unlocked. Anybody tried this? Also wondering out loud how hard it would be to build one of these.