If you really want it to only hold a cell phone I recommend 2 strips of fabric 5 1/2" x 18" and 1 piece of batting (such as W&N) the same size. Sandwich but don't bother to quilt. Near one end sew a 6" piece (fuzzy side) of Velcro lengthwise down the center of the sandwich. Skip 2 or 3 inches and sew the (hook side) Velcro along the same line. On the opposite end of the sandwich: Bind across the end, the fold up about 5" creating a pocket Bind both sides of the sandwich with the pocket folded up. You now have a phone holder the can be hung from a variety of bars or chair arms