I made my GDs regular twin size quilts very plain, but put the outline of a mermaid using the material used for dance and bathing suits , so when they cover up their heads are the heads of the mermaid . I also crocheted them each an afghan mermaid blanket, similar to the pattern. I did keep the tail open for their feet to go through and they have not had a problem walking around with it on. Good luck in what ever you decide to make. I am sure your GD will love it.