One of the key defects in composite materials is the large variability in mechanical properties. To capture the variability of strength in FRPs, random microstructures have to be analyzed. Developing a realistic model for generation of random microstructures required first imaging a carbon reinforced epoxy and then quantifying prominent microstructural features. Microstructures were synthetically generated including experimentally observed microstructural features such as elliptical fibers, alignment fibers, voids, and resin seams. Material periodicity of microstructures was considered to facilitate the application of displacement periodic boundary condition for later finite element analysis.