I was making some Goldilocks-and-the-3-Bears costumes, and was stumped on how to make see-through eyes that looked convincing. Finally I found the answer. I took some big "googly eyes" (wiggle eyes?) and separated the front from the back. I painted a colored iris on the inside of the front, let it dry, and then poked holes with a needle around the edge. Then I sewed the eyes into holes in the costume face. It looks cute and works great! This idea has probably been thought of before, but I just wanted to share!