Well, due to financial hardship, I decided to utilize a laying ARK as my meatie pen. I did build this ARK with the largest floorspace that I could possibly do with the lumber I had at the time (4-weeks ago). My goal was to sell the ARK online and take the profit and purchase more materials for another, or for my meatie pen. However, it seems my market for selling tractors has dried up these past few weeks! SO..I have a 6'x8' framework A FRAME, with plenty of headroom. The benefit of the headroom is ease of hanging feeders, or simply being able to walk in (with a crunch'd back of course) for when I round them up for the freezer. I modified the ARK by taking the lofting area out and then taking the loft and using it for walls on the backside as a wind-block. The other benefit is that it ventilates well, and very inexpensive. I have about $45 in materials. PER JOEL SALATIN's THEORY of 1.33 square feet, I would be optimized at 36 birds. I have 43 in there now, and will probably move a few out when they get a bit bigger to keep his optimized suggestion. Yes, I know you may have a different opinion for optimal square footage, but for my first run I have decided to follow his suggestions as best as possible. I move these guys often, and the tractor is very easy for me to move alone.