I often use old irons to help me hold things on my work table. They are like a third hand! When I make a long cuts, I'll place an old iron at one end to hold the ruler firmly while I cut.
They're great to cut slippery fabrics too. I'll use one to hold the fabric in alignment with my rulers markings while I position my ruler, then move it onto the ruler to hold it firm and make the cut. I have a collection of large beach stones that I can use if I don't have enough irons.