A method of manufacturing a composite insert includes forming a polymer mold from a polymer sheet which may have a glass transition temperature of 70 to 160° C., the polymer mold either includes a cavity or may form a cavity disposed between the polymer mold and the carrier. The method proceeds by depositing a liquid reactive composite insert composition, which may be a two-component composition including a first part comprised of an isocyanate-epoxy blend and a second part comprised of an alcohol-epoxy blend, into the cavity under low pressure conditions of 0-10 bar and low temperature conditions of 15-100° C. The composition is then allowed to become dimensionally stable either within the polymer mold or between the polymer mold and the carrier.