The challenge: Create a rainbow and get it reflected in a curved surface to reveal a rectangle. All credit here to Woolly Thoughts! (They have wonderful things for you to play with there.)
Materials needed: I crocheted mine, which was a fun puzzle to get an even rainbow. They have knitting instructions on their website, but you could just as easily draw this with markers. I used tinfoil as my reflective surface wrapped around a nail polish remover bottle. I bet you all get more creative than myself.