The positions of diffraction gratings used for calibration can be checked easily by arranging marks near the diffraction gratings, the marks indicating the coordinate positions of the diffraction gratings. The optical reflector includes a substrate having a surface to render non-uniform light from the light sources to the SLM’s more uniform with one reflection off the substrate, and a number of facets within the surface of the substrate. The service gateway enables content translation between clients and service providers. In the preferred embodiment, a material dispensing outlet of the dispensing head is inside the chamber.