I've used two golfballs in each nesting box (I have two nesting boxes total) since my pullets were of age to start laying. It must work, because I've only had one egg layied out side the nestting box on the floor once, and that egg was a soft, rubber like, shelless egg. So I give her a pass on that one. Over the past week or so, when I go out to collect the eggs, sometimes the golfballs will be moved. Sometimes there will be three balls, sometime all four, in one nesting box. Why would the chickens move the golf balls from one nesting box to the other? Has anyone ever had this happen?