These simple coasters are made from clay pot drain trays or whatever you call them. I think they are about a 4" or so. I painted them with acrylic paint and decided to add our initials (we have one on each bedside table). I finished with a coat of spray poly. These last and are sturdy for the precarious toddlers in your life! My tot has an infatuation with coasters. He loves them and he loves to rearrange and stack them. At least he always puts his sippy cup on a coaster! Mama's teaching him early how to be a good husband! :)
I'm sure you could get much more creative with this project - so many ways you could decorate them.