Abstract: Apparatus for cutting a sheet of material which includes a base member having a generally planar top surface and a body member having a generally planar bottom surface. The body member has a first slot extending from the bottom surface. A spacer separates the top surface of the base member and the bottom surface of the body member. A bifurcated retainer has first and second generally parallel generally coplanar arms which are disposed respectively in first and second planes passing on first and second sides of the first slot. In some forms of the invention the apparatus includes a cover element and a pivotal mounting for the cover element on the body member. The cover element may have a notch therein for receiving a corner of an associated cutting edge. The pivotal mounting may include a spring bias for urging the cover element toward the body member. The bifurcated retainer may be manufactured of spring steel.