Does anyone out there have a rat-proof coop design, or know of where to find one. My neighbor has a dozen or so chickens in her backyard (which I like) but she also is raising a good hundred or more rats in their along with 'em. I don't mind picking them off one-by-one with my pellet gun, but it's taking up an awful lot of my free time, and I don't seem to be making much headway. I've been asked by the neighbors to come up with a new coop/run that will prevent the rats from multiplying like well, rats. Any suggestions would be greatly appreciated. I live in Portland, OR - right in the city.