This application discloses a mold for making die sets for bumper repair, a method of making the mold, and a method of making the dies. The mold is made from an undamaged bumper section to which extensions are added to make an enclosure suitable for simultaneously casting both of the male and female die members. The welding and a subsequent step of heat treating is accomplished in such a way that the longitudinal curvature is greater than that of the original bumper so that the resulting die set tends to overbend bumpers being repaired. The mold is placed in a flask with side walls and liquid casting metal is introduced inside and outside of the mold, filling the inside and substantially enclosing the outside. After hardening, the flask and mold are removed, leaving a matching, fully congruent die set. The working (pressing) surfaces of the die thus obtained correspond exactly to each other and are true copies of the faultless original bumper segment, except for the added curvature.