This pattern was designed by Patty Paddock (c) 1993. I believe it is still available at "The Fabric Cupboard" in Moncton, NB, Canada. Here is a link to their blog -
http://thefabriccupboard.blogspot.ca...&by-date=false (scroll down to September 10, 2013). She still teaches this class once or twice a year. It really is a very easy technique!