One embodiment of this workpiece handling system has conveyor belts and a load lock. A first swap robot holds and transports workpieces between a build station and the load lock. A gantry robot transports the workpieces between each of the conveyor belts and the first swap robot. In one instance, processed workpieces are transported from the first swap robot to a first conveyor belt and unprocessed workpieces are transported from a second conveyor belt to the first swap robot using the gantry robot. A second swap robot also may be used with the first swap robot to load and unload workpieces from the load lock.