Use the straight side of this double strip ruler to cut 1 ½" and 2 ½" strips or use the pre-cuts that are on the market. Sew these strips together to create a 4 ½" wide strip set. Turn-a-Round the ruler to cut tumblers that finish 4". Multiple layers can be cut at the same time, cutting five tumblers at once without wasting any fabric. The holes in the ruler enable the rotary cutter to cut the tumblers without damaging the ruler.
. See instruction videohere.