A polymer injection-molding mold having a polymer injection-molding mold having a core insert and a cavity insert; at least two rear-wall glass-filled polyimide insulation plates, one of the rear-wall insulation plates being inset into a rear-exterior wall of the core insert and one of the rear-wall insulation plates being inset into a rear-exterior wall of the cavity insert; at least two side-wall glass-filled polyimide insulation plates, one of the side-wall insulation plates being inset into a side-exterior wall of the core insert and one of the side-wall insulation plates being inset into a side-exterior wall of the cavity insert; the at least two rear-wall glass-filled polyimide insulation plates and the at least two side-wall glass-filled polyimide insulation plates being inset into each of their respective walls such that a substantially planer surface of each insulation plate is substantially flush with an exterior planar surface of the respective wall into which it is inset; the rear-wall and side-wall glass-filled polyimide insulation plates having the following physical properties: i) thermal conductivity of about 0.30 W/mk; ii) a coefficient of expansion (in length and width) of about 11×10−6 1/K; iii) a compressive strength of about 750 N/mm2 at 23° C.; iv) a compressive strength of about 500 N/mm2 at 200° C.; v) a bending strength of about 720 N/mm2 at 23° C.; and vi) a density of about 2 g/cm3; the rear-wall and side-wall glass-filled insulation plates having a thickness ranging from 3 to 5 millimeters; the cavity insert and core insert having a plurality of cooling holes, the cooling holes having a diameter ranging from 3 to 6 millimeters; a plurality of substantially cylindrical fluid-cooling channels that are respectively positioned within the cavity insert and core insert at a relative distance from a cavity-insert molding surface or a core-insert molding surface, wherein the relative distance for each fluid-cooling channel is substantially equal to the fluid-cooling channel's cross-sectional diameter, wherein the relative distance is also the shortest distance between a fluid-cooling channel's wall and a cavity-insert molding surface or a core-insert molding surface; and a temperature-sensing thermocouple that is located within the cavity insert or core insert in a position that is substantially adjacent to an estimated last volume of space to be filled by polymer-mold flow.