I've been meaning to figure out how to make one of these for a while so I've been saving cardboard tubes that are approximately wrist size to do it. But I hadn't figured out how to cap the ends to make them look finished and professional. Then it occurred to me that mailing tubes already are the right size and already have end caps. This couldn't be easier. I used a scrap of fabric that resembles white Dupioni silk to match my other displays.
* Mailing tube that is wrist size (this one was 7 inches in circumference)
* Thin fabric of your choice (too thick and the end caps won't go on later)
* Matching thread
Cut a piece of fabric to cover the mailing tube. Measure carefully so that the fabric is just 5/8 inch wider than the circumference of your mailing tube and at least two inches longer. With right sides together sew the fabric into a long tube with a 1/4 inch seam. I used pinking sheers after sewing to trim the seam and keep the fabric from fraying. Press seam open using just the tip of the iron. Turn fabric tube right side out and slip over the mailing tube. It should fit very tightly if you measured correctly. Tuck the raw ends into the tube and slide the end caps on.