Abstract: An apparatus for accurately and conveniently locating on the surface of a building panel the location where such panel is to be "cut", i.e. sawn, drilled, cutout, etc. The apparatus comprises a planar body conforming generally to the shape of the panel and which can be superimposed both on the panel and over the work area where a panel will eventually be placed. The planar body is provided with a matrix of openings as well as with markers. When the body is superimposed on the work area, the markers are placed through the openings corresponding to the location of the required cuts and the body is then superimposed and registered with a panel; whereby the markers indicate on the surface of the panel the portions thereof to be cut.