Abstract: A tool for effecting precision layout is provided with a translucent support surface and means for accurately positioning a straight edge in any of a number of preselected positions spanning the support surface. Apertures through opposite ends of the straight-edge element are selectively alignable with spaced rows of precision indexing holes which circumscribe the support surface. A pair of locator pins are removably disposed within said apertures projecting into selected indexing holes to accurately locate and retain the straight-edge element in a desired position across the support surface. A related registering method is provided which utilizes accurately positioned, perpendicularly intersecting lines to locate image transparencies upon a masking sheet as well as to register superimposed color impressions during printing.