A process for treating a substrate such as glass or wood to provide the appearance of concrete. A system is also disclosed for multicasting targeted advertising data to end user devices. The system then associates nodes with features in the layout, and generates arcs between the nodes. Frequencies of the first and second repeated waves exclude natural frequencies of a mechanically-vibrating system of the mirror with respect to the axis thereof depending upon the piezoelectric actuators. In a preferred embodiment utilizing a light emitting diode as the light source, the combined light beam produced by the light assembly has a substantially circular cross section.