1. Stand holding the sheet by the two adjacent corners of one of the shorter edges. With the sheet inside out, place one hand in each of these two corners.
2. Bring your right hand to your left, and fold the corner in your right hand over the one in your left, enveloping it. Next, reach down and pick up the corner that is hanging in front; bring it up, and fold it over the two corners in your left hand; the corner that's showing will be inside out.
3. Bring the last corner up, and fold it over the others; with its right side showing, it should envelop the other three corners.
4. Lay the folded sheet on a flat surface and straighten it into the shape shown.
5. Fold the two edges in so all the elastic is hidden.
6. Fold the sheet into a rectangle.
7. Continue folding until the rectangle is the size you want it to be.