I really like this picture a great deal.  It has so much fine detail that really can't be seen here, but can in the bigger picture.  One day I was experimenting with what happened if you took a semicircle and started to rotate it around the page.  I just kept going with the idea and ended up with a drawing that looked similar to this.  Once I started to make the mobile, I modified it a bit to fit in the frame and Voila!