Print sewing pattern on cardstock paper at full size. Cut out pattern.
Trace pattern on suede / leather using pen or marker, then carefully cut along lines.
Cut a strip of material ¼-inch wide by 25-inches long. Trim one end on an angle.
Lay the case flat with inside of material facing up. Align the flat edge of the strap with the middle of the case.
Using a needle and thread, sew the strap in place using an x-pattern. Go over the "x" a few times, then knot your thread and trim the ends.
Attach the strap to the bottom center of the case with an "x", as well. (Do not attach the middle part of the strap to the case.)
To use case, slide one of the sunglass temples (arms) under the interior strap. Close the case, then wrap the strap around the outside a few times. Tuck the loose edge under the strap to close.