Those stupid binding tools for joining the ends. What's worse, I have two of them. Granted, they didn't cost that much, but I found a YouTube video that showed me a fast, EASY, way to do it.
Also, one of those 'gripper' things with suction cups to keep your ruler from slipping.
And, a ruler with a groove on the side to guide the matching rotary cutter. Never could get the hang of it.