PBR and cell data for metallic & roughness

With PBR, is it possible to use cell data to specify metallic and roughness properties, instead of in the vtkProperty of the actor? Our actors typically have a vtkCompositePolyDataMapper2 taking as input vtkMultiBlockDataSet with blocks of varying materials. If each material (or material class, e.g. concrete, masonry, soil, rock, … ) would require its own actor this would increase the number of actors considerably.