The issue of mobility raises another point I was going to make - even for those not wishing to use the setup as an active "tractor", the ability to pick up and move the coop if/when needed is key. My recent purchase completely lacks places where a good grip can be gotten that does not risk causing some part of the coop to fall apart or break (the only exception I found was to pull out the tray and use the opening for it - but that only gives you a grip on one side). We used the bottom, but getting your fingers down in there and getting a grip was difficult and even then the issue of the weak wood caused structural failure. A well built coop that will hold together WITH built in handles, etc. (or wheels for tractor applications) allowing for grip, lift and carry would be at the top of my list!