We have 6 chickens and lots and lots of egg shells!
Use #1 is compost. Many plants benefit from the addition of minerals to the soil. Especially tomatoes and strawberries.
Use #2 is in chicken feed. I always get a little nervous about this. Some people feed them right back to the chickens but that makes me c!r!i!n!g!e I would suggest if you are going to do this, bake them in the oven first to avoid spreading pathogens between the chickens. Ideally, put them in with something else so you don’t use any additional energy. Use #3. Confetti eggs! Save the punch outs from you hole punch to fill them up! If thats not enough, try to get your friends to raid the hole punches at work. Only add new confetti if you need more colors.