I avoided egg eating when the eggs have to remain in the nests due to my work schedule...I work 12 hr shifts...before my birds started to lay...I put ceramic eggs in each nesting box..partly to attract the birds and partly to discourage egg eating...they check out the "eggs" try to peck them...nothing happens...they don't break...the birds lose interest in trying to eat them...it's rare to find a broken egg...might just be luck....
We removed the cross bar separating the coop from the nesting boxes, trimmed the new roll-away tray a bit on the sides to fit and then my husband secured the back side of the trays to a block of wood (to angle it more downward). It did make the coop area itself a little smaller and the hens had to crawl over the egg retrieval section to sit in the laying area of the new tray.
However since that time, he's built me a larger nesting box (both longer & wider). The 2 roll-away trays now sit in there better with the egg retrieval flap towards the back side of the box. Although this project and tweaking has greatly increased my ability to retrieve edible eggs; it's not 100% fool-proof. Sometimes the eggs are too big to successfully roll into the tray and my bigger Plymouth Rock hen still prefers to just sit in the corner of the coop and lay there (most of her pretty eggs are broken & eaten unless the timing is perfect in my retrieval). I too had tried the dummy eggs (used plastic Easter eggs), put my egg eaters were persistent and still broke & ate the real ones. It's a frustrating and contagious bad habit, I'm afraid. Good luck with your efforts and thanks for posting.
