Abstract : The DARPA program involved investigating the assembly of 3-dimensional optoelectronic/microelectronic components with optical precision. A three-active-facet retromodulator with multiple quantum well modulators on the three faces of a comer cube was constructed. The comer cube was made using FR4 printed circuit boards (PCB's) utilizing standard microelectronic machining equipment. An active retromodulator, utilizing large-area multiple quantum well modulators on 3 faces, was demonstrated, and a high modulation contrast ratio of 8.23dB was shown to be achievable. The large-area devices were fabricated using substrates made by metalorganic chemical vapor deposition. The proposed target angular error in the module face angles was +/-0.5 degrees. However, errors of +/-1 degree were achieved in the comer cube modules. These angular errors can be corrected by using readily available off-the-shelf optical components to achieve true retroreflection, with additional bulk to the system. Alternatively, the PCB's can be mounted directly upon a precision comer cube with additional cost to the system. The large-area multiple quantum well devices fabricated from substrates grown using MOCVD have a lower defect density than those grown using MBE.