Many years ago I had this idea to build a box 4'x18"x18" that I cut four holes in and placed doors on. I then placed my entertainment center on top. The box was used for toys for my grandchildren in the living room. Well When the chickens came along then I needed nest boxes and was short on cash so I had the brilliant idea that I could use this box for the ladies. I removed the top and front wall and sawed the sides at an angle for the roof to set on. I then screwed/nailed it to the outside wall of the coop. I then took my saw and cut the holes out for the ladies to get in. Replaced the top, after putting some rolled roofing across it, with a couple of hinges for access purposes. Put hay in it and a golf ball in each of the four nests. When the ladies started to lay they went right in and laid in the box. I found that they liked to kick the hay out which resulted in cracked eggs when they hit the wood bottom so I laid in a piece of carpet that I had removed from the living room. Replaced the hay and golf balls and voila no more cracked eggs.
I had to use carpet in mine too. No matter how high of a lip I put across the front, they still managed to kick out all the shavings.