I just finished building my coop pop-door, which turns out to be guillotine style. It has locks to hold it in the open position and locks in the close position. I don't know why it didn't occur to me earlier, but the second I finished the pop-door I thought, "what if in the off chance one of my chickens walks underneath and I accidentally lose grip of the pop-door and it goes crashing down on her. This is a scenario I can't quite get out of my head. My pop-door is about 9x12 made out leftover plywood about half-inch thick. Why are guillotine doors so popular? Why would any door designed to be held open against gravity be good? Seems rather unsafe in case the hold mechanism fails or the more likely scenarios: user error. I'm starting to think I should have built a swinging door or a sideways sliding pop-door. This is kind of disappointing . Please tell me what's good about guillotine style pop-doors! I am considering adding a spring or something to the pop-door anchored to above the door, so when it's balanced the door is half open and would apply tension when the door is closed, but I'm thinking at least in case the door slips hopefully an accident can be avoided.