My daughter wants to be Ariel (little mermaid) for halloween. The only costumes I've seen are the princess dress versions. She HAS to have a tail. So I decided I would make it. Well I was lucky to find a clearance window curtain in a shimmery green/blue on at walmart for $5, so I go PLENTY of fabric. So I need suggested on how to create a mermaid tail, that she can walk in?