This would be easy to do with wide piece of elastic & 2 yds of material attached to a tank top. Scattered Thoughts of a Crafty Mom: Guest Post: Urban Princess Dress Tutorial from Domestic Bliss Squared
The Best T-Shirt Dress. This pattern is meant for the Dress A Girl Around The World charity. It's a great dress, especially the bit where she uses iron-in interfacing to prevent stretching out the t-shirt all weird while you sew.