The entire pen is 4x4x8. The front run part is half 4x4x4. I built them as brood pens originally. They are pulling double duty though since I have 25 chicks in them right now. If you do a google search for 4x4x8 brood pen a link comes back to this site with instructions how to build it. I don't want to take credit for someone else's ideas. They are simple and for the complete pen all you need is 13 2x4x8, a gate latch, two hinges, two sheets of plywood some deck screws, roof material and whatever wire you want. I've only got 4 built so far,need to build 6 more. Wood and wire ain't cheap though so I'm gonna have to make some domes like you have or something similar. Too many hawks and fox for tie cords here.
I am going to look into the design for use as brooder pens. Are they easy to move? I like to move pens every week or so allowing birds access to greens and allow the ground to rest making worm management easier.