The invention relates to composite compositions having a matrix of polymer networks and dispersed phases of particulate or fibrous materials. The matrix is filled with a particulate phase, which can be selected from one or more of a variety of components, such as fly ash particles, axially oriented fibers, fabrics, chopped random fibers, mineral fibers, ground waste glass, granite dust, or other solid waste materials. A system for providing shape and/or surface features to a moldable material includes, in an exemplary embodiment, at least two first opposed flat endless belts spaced apart a first distance, with each having an inner surface and an outer surface.