I made this one out of a women's medium shirt. Luckily for me, the length was just right, so i didn't have to make a hem. I made the straps just flat, and left some extra at the ends for adjusting. I also cut armholes out, in case I ever want to attach sleeves (with leftover fabric) I now have about 10 shirts I want to do this to (including a men's flannel...will be so comfy). Thank you Cheytown for the fab. tutorial!
Please excuse the wrinkles....didn't have a chance to iron it yet.