My chicken coop is a "masterpiece". As in master piece of scrap. It was cobbled together from recycled building materials before I had any experience with keeping chickens in a coop.
My daily chicken chores have given me an education via frustration. One thing I did right was to build it with screws instead of nails. (I love my DEWALT battery tools). My hammer drill and screwdriver bits got a workout.
First error: Not enough floor space. I took apart the storage "room" with the hammer drill and a crowbar. After the first day of hesitation the chickens were scratching around the "new" section like it had always been there, yay!
Second error: Not enough nest boxes. I added another nest box below the original elevated nest box. I screwed up (heh) walls around it, including a removable entry wall with a little chicken step. Knowing how much they love change, I walled off the original nest box so they would learn to use the new one. They gave me the stink eye and left five eggs in the new box, yay!
Third error: Litter falls out the doors. I cut corners off of short boards to make guide channels. Then I screwed up the guide channels to the door frames and placed baffle boards in the slots to keep litter in the coop and still allow human and chicken traffic. This was a real trial because I had to limbo under the roosts. The whole flock came in to help and it was chaotic for a while. I got mooned by a hen and collected the glare of death from the rooster, but we got everything sorted before it got too dark for me to find my way out of the coop. Now the chicken ladder and people step are both clean, yay!
Fourth error: Poor roost placement. This one was a huuuuuge mistake. The birds like it just fine, but I never want to be trapped behind the roost ever again. Ever! For now, I have removed the old roosts and put 2x4 roosts in the "new" section. This caused a great deal of consternation. They looked everywhere for the old roosts -- in the nest box, on the waterer, outside the window, and under the ladder. It was obviously hiding from them, so they eventually gave up and used the new roost. Well for a little while. When I checked on them again they were all piled into the upper nest box. Brilliant.
Fifth error: Food and water on the coop floor. This was another huuuuuge mistake. I bought a hanging feeder and installed it. Big improvement! The double walled waterer is still on the coop floor and they often poo in it. I plan to hang it up, or else buy a nipple waterer. Argh! Hanging it was a baaaaaad idea.
Sixth error: Poor access to fresh eggs in nest boxes. OK, I am about as good at carpentry as I am at cooking. It is one thing to play with the big boy toys and drill, cut, hammer, and screw things into more or less the right place. It is quite another to make a sturdy, level, square, hinged, safe, weatherproof nest box hanging out the side of the coop. Note to self: learn this soon. Future project.
I am only half way through my list and I have already run out the battery! Oh well, I need to recharge too.
Update: Added bird net to pen. It keeps the formerly-free-ranging chickens confined!