Continuous fiber tow structures are used to form lattice reinforcing bodies to be embedded in a molded polymer matrix. The lattice structures are formed and shaped to reinforce a portion of a predetermined three-dimensional article. Optionally, some or all of the tow members of the structure may be formed with internal vascular passages for passage of a heat transfer fluid through the structure in the function of the molded polymer article. A liquid polymer is molded around the lattice structure, fully embedding the structure. The liquid polymer which may contain short-reinforcing fibers, is then solidified to form the composite reinforced polymer article. And connections may be made to the composite article for the flow of the fluid through vascular passages in the lattice structure within the article.