Select a cotton fabric rectangle and square it up with rotary cutter and straight edge or mark with straight edge and cut with scissors. Select a long edge, or an edge if fabric is a square. Using a seam guage, fold edge over 1/2″ and secure with clips. Fold over same edge a second time at 1/2″ and clip. If one is careful, both folds can be executed before applying clips. Sew seam 1/16″ – 1/8″ from inside of folds. Repeat folding, clipping, sewing with opposing edge, then opposite edges, one at a time.