Have fun with the Jade Collection of Rulers - Handi Quilter's 4th Ruler Collection.
You can see how to use it with the Jade Ruler on this link. It gives you the crosshairs needed to use a rotating ruler such as the Jade Spin-E-Fex
Watch accompanying videos and download a PDF for design ideas.
This crosshair ruler can be used as shown in the Westalee Ruler demonstration on this link