The most useful specialty ruler I have is my 60* triangle ruler. I use it for OBW and I also used it in my Boxes of Strings scrappy I am working on. I could have bought the recommended Boxes Of Strings triangle ruler but I used what I had. I also use a little 1/2 inch ruler I got at the thrift store for .50 cents. It is real handy for marking the sewing lines on a 2 squares for 2 half square triangles. [ATTACH=CONFIG]596278[/ATTACH]