A device for producing a spacer by curing bone cement paste , wherein the spacer is provided in the medical field for temporarily replacing a joint or part of a joint comprising an articulating surface of a head of the joint, in particular for temporarily replacing a hip joint or a shoulder joint, the device having a stem mold for shaping a stem of the spacer from bone cement paste , wherein the stem mold has in the interior thereof an inner space , wherein the inner space is accessible via a proximal opening on a proximal side of the stem mold and wherein the stem mold has a proximal wall which peripherally delimits the proximal opening of the stem mold , a head mold for shaping a head and a neck of the spacer from bone cement paste , wherein the head mold has in the interior thereof a hollow space , wherein the hollow space has a spherical surface-shaped inner surface for shaping a sliding surface of the head of the spacer and the hollow space is accessible via a distal opening on a distal side of the head mold , wherein the head mold has a distal wall which peripherally delimits the distal opening of the head mold , a metal core , wherein the metal core has a stem part , a head part and a flange , wherein the flange projects out from the metal core , wherein the flange is arranged between the stem part and the head part and wherein the flange has a proximal surface and a distal surface , characterized in that the stem mold and the stem part of the metal core are shaped such that the stem part is arranged in the inner space of the stem mold , when the proximal wall of the stem mold is resting against the distal surface of the flange , and the head mold and the head part of the metal core are shaped such that the head part is arranged in the hollow space of the head mold , when the distal wall of the head mold is resting against the proximal surface of the flange . a stem mold for shaping a stem of the spacer from bone cement paste , wherein the stem mold has in the interior thereof an inner space , wherein the inner space is accessible via a proximal opening on a proximal side of the stem mold and wherein the stem mold has a proximal wall which peripherally delimits the proximal opening of the stem mold , a head mold for shaping a head and a neck of the spacer from bone cement paste , wherein the head mold has in the interior thereof a hollow space , wherein the hollow space has a spherical surface-shaped inner surface for shaping a sliding surface of the head of the spacer and the hollow space is accessible via a distal opening on a distal side of the head mold , wherein the head mold has a distal wall which peripherally delimits the distal opening of the head mold , a metal core , wherein the metal core has a stem part , a head part and a flange , wherein the flange projects out from the metal core , wherein the flange is arranged between the stem part and the head part and wherein the flange has a proximal surface and a distal surface , characterized in that the stem mold and the stem part of the metal core are shaped such that the stem part is arranged in the inner space of the stem mold , when the proximal wall of the stem mold is resting against the distal surface of the flange , and the head mold and the head part of the metal core are shaped such that the head part is arranged in the hollow space of the head mold , when the distal wall of the head mold is resting against the proximal surface of the flange . <EOS>