My uncle had a huge flock of layers for egg sales.
He had a side gig as a groundskeeper at a golf course. He had a bucket of balls in the henhouse and every nest had a golf ball in it.
I originally made fake eggs from water putty. They worked pretty well.
If they are roughly the same size and...
They aren't absolutely necessary but I use them and find them helpful. It shows the pullets where a safe place to lay is. If you get an egg eater, they deter that since they can't break them.
I don't know how many hens you'll have but you can get 2 at some of the feed stores or you can get more...