When I started a quilting class for a couple of co-workers I insisted they get a self-closing cutter and, told them my #1 rule is not to work with sharp objects when tired. One of them did buy a kit that contained another type of cutter plus she bought the one I suggested. When I asked to see the one that came in the kit, it slipped out of my hand and bounced on the table onto the floor. Certainly did hammer the lesson home!