Start with a man's shirt. Cut off the sleeves and the back. Cut around the collar but leave it intact. I cut very close to the seam so that I wouldn't have to hem anything or have any raw edges. Use your rotary cutter and ruler to make a diagonal cut from the armpit to the top of the shoulder. Make sure both sides are even. On the raw edge that you just cut, turn a hem under, concealing all raw edges, and sew it down. Do this on both sides.