Welcome to the quilt board!
Cathedral windows take a lot of handwork if done the old fashioned way and thus take a long time to get done. You might want to check out this ruler and pattern. It is from Missouri Quilt Co and it is reminiscent of the cathedral window quilt but would not take too long at all to get done. There is a video on how to use it and how the quilt would look.
http://www.missouriquiltco.com/circl...-brandy-s.html