My husband and I are building a very small coop like the Nags Head coop, which is built on a rolling cart. We are also building a run which will not be permanently attached because we want to be able to move both around to fresh grass. We live in the woods with lots of predators, so my greatest focus is on safety. We will be using only 1/2" hardware cloth on windows and the entire run. Now, this is where I am stumped -- I can't envision how to construct a pop door on the coop and an opening in the run that will be secure. In other words, I want the connection between the two to be secure, but I haven't come across any photos here of a close-up of this area. I wanted to make an actual framed area in the portion of the run that would connect to the pop door which would be "fitted" to the pop door, so that there would be no room for access between the run and the coop. Am I making sense? Ideas, anyone?