The production of continuous lengths of fiber-reinforced advanced composites. Fibers are fed as roving, fabric, or mat, or some combination of these, through a resin impregnation process, to a forming guide, then to a heated die to produce a specific shape, and finally to a puller where the structure is pulled through different forming and cooling stages. Thermoplastic fibers may be substituted for the resin in the pultrusion process to simpler chemical units as a result of pyrolysis.