There is an excellent tutorial posted by bethany at the Vermillion Rules blog that describes precisely how to make a little girl’s tutu with only some elastic strap, a few yards of inexpensive and easy-to-find tulle, and no sewing. (I didn’t sew the elastic together as the author suggested; I just tied it into a knot instead.)
Check out the full tutorial here: An Extremely Detailed Tutu Tutorial.
The end result: A very happy little girl!