A robotic system for laying out a specified wiring harness. A robotic arm is configured to arrange a plurality of wire segments along the harness support surface. A system controller is configured to direct the robotic arm to arrange each of the plurality of wire segments on the harness support surface along a specified wire route. A preparation device can label one or both ends of each wire segment as they are being laid out on the support surface. The labeler can automatically apply adhesive labels as flags at selected locations along the length of the wire segment. In a method of making a wiring harness, the robotic arm positions pins on a harness support surface to define wire routes and then arranges at least one wire segment on the harness support surface along each of the wire routes.