Cut out the part of the pattern you want to be etched using a craft knife. We cut on all sides of the dark portion of the Greek key pattern. Be sure to make precise cuts, pressing firmly so that the knife cuts through both the pattern you taped down and the adhesive paper. (You will not harm the mirror with firm pressure.) When finished cutting, carefully remove the pattern and the cut-out parts of the adhesive paper, exposing part of the mirror. You’ve created the stencil.