I've made a whole bunch of these using old shirts, with more or less success, sometimes complete failures. I think I've finally got it. I'm using XL t-shirts from Kohls, either Croft & Barrow or Sonoma. The jersey fabric is about 20 inches long and works best if it's a little wider than the diameter of the shirt (this one was a little puckered because it was a bit shorter), about 46". I cut the slanted on the sides to get a little bit of swing and add in one pocket. They come out about knee-length.