Measure the rough distance between your shoulders by sticking your arms straight out in front of you.
Fold your fabric in half lengthwise and lay it flat.
Cut a 5-inch slit half the distance between your shoulders away from the center fold. You'll want about a hand's length between the bottom of the slit and the bottom of the fabric on one side. The larger stretch of uncut fabric on the other side will make up your hood and the draping folds in the front of the vest. Because your fabric is folded in half, this actually leaves you with two symmetrical slits that act as arm holes!
Round out the slits a bit with your scissors (but not too much, your shoulders will do that as you wear the vest).
