Orientational optomechanical media, consisting of three dimensional arrays of elongated metal coated dielectric beams suspended by torsional springs, was fabricated using microelectromechanical system (MEMS) technology. Response of a single rotating element to a polarized electromagnetic radiation was found to be in a good agreement with theory. Spatial grating formation in fabricated orientational optomechanical media was detected and measured under the influence of two orthogonally polarized electromagnetic fields at 15 GHz. This process demonstrates the feasibility of using optomechanical media for phase conjugation, via degenerate four-wave mixing, and for other nonlinear processes at microwave and millimeter wave frequencies. ©1997 American Institute of Physics.