A dual roller powder spreader assembly for use in layerwise manufacture in a powder bed fusion additive manufacture process utilizes in an embodiment tilting of the dual roller assembly such that a lead roller is raised upwardly relative to the powder bed in a sweep. This is accomplished using a mechanical cam-like engagement initiated at each end of the assembly's travel, causing what will then be the lead roller to rise as a whole relative to the now following roller, the latter pushing the powder pile across the powder bed. The tilt process is reversed at each end of travel.