I have one and only one ruler that I use for everything..it is the Fiskar ruler with the attached rotary cutter...Luckily the company will be making them again sometime this year..I have had mine for 10 years, and am afraid of what will happen to me if it ever breaks!! As long as you know the measurements for the triangles, you should be able to cut them without a special tool..I think they make you feel like you need a new one, to increase sales!