The tutu activity was another one of our teen-lead activities. All you need is some elastic and a mountain of tulle (a yard makes a little less than a quarter of a small skirt). You can sew the elastic to itself, use stitch-witchery, or you can knot it. Yards of tulle can be cut into long strips, or you can buy tulle on a spool (rhyming is fun!). The length of each piece of tulle is twice the length of the skirt. It is a great activity, just make sure you get a lot of tulle.
Here is a video that is very helpful: