Roll away nests are the final passive solution. The stewpot is the final, FINAL solution.
Egg eating starts because hens are clumsy, often crammed into crowded nests. They stomp around and eggs get broken.
So make sure the nests are big enough and add some padding. 4" of clean litter should do it, with a front rail to hold in the padding.
They dont move around much in the dark, so hang a curtain over the front of the nest to darken it. They also dont eat what they can't see.
Collect eggs early and often to remove temptation.
Replace them with golf balls. Shell try to peck them open, get her head rattled by the hard ball and may give up. MAY give up, as in maybe.
All that is well and good, but once the habit begins it is unlikely to stop without serious intervention. This is where roll away nests come in. AS the name implies, the egg is layed - and rolls out of reach of the hen. There are many good designs. Just do a google search for them. I found a good design on
ebay for a few bucks.
In the old days, an egg eating hen was culled. There was little fanfare or heart-tugging concern for a pet chicken that had the habit. As soon as the hen with egg on her face was spotted, she was removed. Permanently.