Abstract: A plotter and method for laying out computerized construction plans on a construction site includes a mobile applicator (A) carrying a locator (B) for supplying location data to a central processing unit (C) which stores the construction plans, and provides an output signal to an actuator (D) for initiating marking of the site by the applicator. An operator manually traverses the mobile applicator over a path calculated to cover the entire construction site, and the actuator causes the applicator to progressively mark the site responsive to signals from the central processing unit, so that the marks on the site correspond with the construction plans.