The pattern is in the book "Strip Pieced Quilts: Easy Designs from Just Six Fabrics" by Maakie Bakker. Also see the "Take 6" pattern from Australian designer Chris Timmins, who teaches this in her Designing with Strips workshop. Here is a link to the Bakker book on Amazon: http://www.amazon.com/Strip-Pieced-Quilts-Easy-Designs-Fabrics/dp/1564776395/ The name of the quilt in the Bakker book is "Optical Illusion".
Beautiful quilt made by one of our shop gals, Carol!
DQS11 Quilt, finished, and in the mail, hope you like it partner! by shecanquilt, via Flickr