Abstract: A small, hand-held tool enables rapid and repetitive placement of window and door casing. The tool is formed from three distinctive, generally rectangular layers. The center, sandwiched layer extends beyond the outer two layers by an amount equal to the desired offset or reveal of the casing. An extension protrudes diagonally from one side of the center layer and forms a one hundred and thirty-five degree angle with an adjacent side. This extension enables the tool holder to accurately place the corners of each casing strip, after the strips have been cut at the normal diagonal forty-five degree angle. A hole through the center of each of the layers provides for easy and solid grasping and manipulation. Scribe marks may also be provided, to more readily assist the tool user to mark, measure or visually discriminate various distances and geometries. Additional alternative features are further described in the disclosure.