As many have already said, sufficient calcium from food, oyster shell supplements, or dried eggshell; soft bedding for the next box. I was unable to alter my nest boxes into roll-away and the attempt at curtains scared my birds away from box. When my newest hens started pecking at and eating eggs (due to one on the ground that was broken and they discovered it was delicious) I got some old golf balls from a coworker. Each next box has 1-2 gold balls in it. This helped the chickens ensure they were laying in the box not the ground, and stopped the attempt to peck and eat the eggs in less than one week. Good luck in your endeavors!