Okay, this technically wasn't my idea. I have an extremely imaginative boy.
I got out a stack of embroidery hoops because I had some ideas for them. Boo wanted to run around with them, so I let him. A minute later, I heard him saying, "Look at all the beautiful butterflies!" He was two-fisting the embroidery hoops and waving them up and down so they flapped like wings. They did actually move like butterflies. I took the screws out of two and then linked them together.
I was thinking I would find some patterned fabric and stretch it inside the hoops. Then Boo bashed the "butterfly" into something and it splintered into several sharp pieces. I guess embroidery hoops are not meant as toys.