Abstract: A guide facilitates marking or cutting flat sheet material, such as wallboard or plywood for example, along linear or arcuate lines. A first guide member has a flat surface which is contacted with an edge of the material. A swivelable guide member is pivoted to the first guide member and carries a tape measure having a housing containing a coiled measuring tape that can be drawn outward from the housing. An implement receiver at the end of the tape has an opening sized to receive a marking pencil, scribe or the like and a slit opening sized to receive a knife or scoring tool blade. A clamp immobilizes the tape relative to the tape housing at any selected degree of extension from the housing. Linear markings or cuts, parallel to an edge of the material, are made by traveling the guide member assembly along the edge while simultaneously traveling the implement receiver along a parallel path.