I, too, have a small ruler collection. I have a couple of square rulers and a 6.5" by 24", but the one I use the most is
2" by 18". It has a "knob" that makes it easy to grab and 1/8" markings. Definitely added traction gripper stick-ons to the backsides.
I forgot about the clear
6" by 1/4" ruler that I use a lot.