This thread has been a lot of fun to read! But I have a practical alternative. When my chicks were younger, we couldn't tell them apart. We used a cable tie to make a kind of bangle bracelet to put on their legs. The ones we put on in June are still there. You can see a pic of Mary Lou with her yellow one on my page: https://www.backyardchickens.com/web/viewblog.php?id=52059-the-chickies
HTH
HTH