We are still working on our coop but here is what we have done so far. The coop is 12'x12', we built the floor out of 2x6x6 pressure treated lumber, we built 4 6'x6' sections then covered them with 1/4" hardware cloth, screwed in with 1-1/2 screws and 1" fender washers, then we turned the sections over with the hardware cloth on the bottom and set them on concrete blocks. The four sections are bolted together at the center and on the sides.
Then we attached hardware cloth to the sides and ran it out 2' along the ground overlapping on the corners and held it down with earth staples. After the walls were framed out and siding added, the siding goes down over the edge of the hardware cloth and helps to hold it. We have 9 metal vents 12"x12" at the top around all four sides, these were then covered with 1/4" hardware cloth on the outside with screws and washers and also on the inside, the studs were set to match the vent opening so the screws go into the studs on both sides. The doors have 2"x6" frames and heavy duty hinges and two heavy duty latches. We have 8 crank out windows, we couldn't put the hardware cloth on the outside so we built frames out of 2x4's that fit inside the windows, covered them with the hardware cloth, also screwed in with fender washers, we inserted them and nailed them in, we left the nails sticking out slightly so we can remove them easily. The pop door has an inside door made from a heavy plastic cutting board which is sandwiched between two metal tracks, it slides up and down, and is held open by sliding the metal loop at the top over a nail, the outside door is made of 2x4's and is hinged to pull up, it is held shut by a sliding glass door latch on the inside. They both open from inside the coop, the outside door will open with a cable run thru the wall. We have not finished the run but it will be 4x4x8 posts set in concrete covered with 1/4" hardware cloth on the sides with an apron, and the top. We also will be surrounding the run and the coop with electric fence.
We have fox, stray dogs, cats, raccoons, snakes (I hate snakes), and black bear. Our neighbors (about 1 mile away) free range their chickens and don't seem to care if they lose them, so I hope that our coop will be secure enough that the critters will continue to visit them for their chicken meals and leave us alone.