When I make a zipper. I use a leather thong, running through the springs, I tie a knot on each side of each clothes pin. not tight against it, I leave room for movement side to side. then tie off the ends. Depending on the level of pain you want to induce, or kinds of marks you want to cause. making the springs tighter or more loose by stretching them open or closed. Depending where you want to apply it varies on what kind of tightness of the springs you want. Using some 100 grit sandpaper you can round the long edges of the clamping part so that if the clothes pin slips sideways it doesn't cause unwanted pinching.

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