When I first started quilting, many moons ago, I must have thought I needed a ruler for every block made. Most of them are still in the package unopened! The last ruler I remember buying was by Marti Michell called wonder triangles, which I've used a lot. With BH mysteries I used a number of those unopened rulers. Today, I do not buy specialty rulers, period. If I can't figure out out how to do it with what I have, I don't do it. As it is written: "There's nothing new under the sun".