I began my coop by reading chickens for dummies and then asking questions on the forum. I am looking for about 40 eggs per week and have acquired 7 Golden Comets - I figured I needed about 4 square feet of coop space and 70 square feet of run. I came up with designs for a 4 x 8 coop and 5 x 16 foot run. I have a big yard and wanted to build a tractor and had an old garden cart that I put the coop on. The cart was only 3 by 4, so I had to extend out a foundation on top of the cart. The walls are 4 feet high plus a gabled ceiling of another 12 inches. The ceiling is insulated with an inch of rigid foam. I put six inches of ventilation on both side walls, with hinged flaps that can be closed as needed. The flaps are split so I an close half if I want to. There are three nest boxes mounted externally on one end with a roost area and poop board at the same end of the nest boxes so I can remove the poop board from the same hinged cover that I collect the eggs from. The foundation was 2 x 4's but I used 2 x 3's for all the other framing lumber; it was cheaper and lighter to work with. I scored some blemmed exterior plywood for the floor, sides, and roof at $5 a sheet, used some roof shingles left over from the house and bought a piece of linoleum for $60 for the floor and poop board. I also splurged on an automatic chiken door from Foys for $230. The run is two 16' 2 x 4's for the foundation, framed up with 2 x 3's. The walls of the run are 5' with another foot of gabled ceiling. Everything is covered with 2 x 4 welded wire. I found some nice wheels at TSC on clearance for $7 apiece which I put on hinged blocks. I plan on putting a tarp over the run for shade and rain protection. All told, I think I have about $500 invested in materials, though I haven't really kept good track of it. I went back to the hardware store many times for deck screws and a "few extra 2 x 3's". I've included some rough drawings which got me started, but you can see from the pictures I altered some of the plans.
I very much appreciate all the advice I got on the forum and my comets are doing well.