Thank you all for your generous comments. For those of you asking about the pattern for the tree skirt follow this link
http://creativegrids.com/acatalog/video-demo.htm
to Creative Grids and watch the demo video using the 120degree triangle. She decribes verbally how to make the piece shown by her, into a skirt. The star can be accentuated more in 3D if you chose colours carefully. I used up some of my Christmas fabric that I have had for ages. I hope the link works, and you enjoy making the skirt. I bound the edges of mine, but you I suppose you cound envelope it and just fancy stitch around the outside edges, before the cut out circle in the middle is bound.