This stencil was designed to help to cut the corner of an acetate plaque rounded with a circle of 50mm of radius. It can be replaced with anythingwith this radius, a rule, or just cutting the corner with another shape, but the main idea of this stencil is to help to avoid scratching the plaque when aplying pressure on it. It can be used cutting directly with a trench, or drawing the line and cut later with a scissor.
I design this to be used on this mask, although it can be used with any acetate / pvc / pet plaque:
