I have these rulers and have no problem at all. I bought the tiny rotary cutter to use with them but found it's too small to fit in the slots. A regular size rotary cutter works better. I had no problem with thickness when I sewed the shapes on the background for heart blocks and I frayed them. I sewed a tiny stitch around the heart and then clipped close to the seam. I left about 1/2 inch for fraying as I wanted a smaller fray outline . I used a wire brush to fray the edges. You can buy the small size ones at a hardware store. Looks like a toothbrush.