Clearview 60° Triangle Ruler - 10"
I use this tool to cut the wedges for the Hexie Garden Quilt but it has many uses. It is the best size for 60° log cabin blocks.
If you only want to buy one ruler that can measure and cut almost any size and is still easy to handle, this is the one. The extra diagonal lines allow for keeping the 60 degree angle true. The right tools make the process so much easier!