We have had our share of "Oops!" over the last couple of years when collecting silkie eggs from the 5 different pens. We have tried various ways including hanging a pencil in each pen and marking before leaving the pen. However, my DD's grandma helps to take care of our birds and has severe arthritis in her hands and holding the eggs and writing on them is difficult. I thought and thought about possibilities and came up with this idea. I used a piece of kids sidewalk chalk...one color in each pen. I used a ziptie to attach it inside the pen right by the nesting boxes. Now she just picks up the eggs, swipes the egg across the chalk leaving a small colored mark on the egg. She can use one bucket for picking them all up, then when she gets in the house she sorts the eggs by color into the cartons.