Segmented pressware die set with anti-twist guide keys

A heated, segmented pressware die set for making pressware containers from a paperboard blank includes a plurality of guide keys mounted between at least one of an inner member of a punch or die and an outer ring which reciprocates independently. Each guide key extends in an outward direction from the central axis of the die set. The guide keys are positioned, configured and dimensioned to engage the outer ring in order to limit rotation of the outer ring with respect to the inner member of the punch or die. In a preferred construction, the guide keys have radially extending planar surfaces which cooperate with guide channels having like surfaces such that clearances necessary to accommodate thermal expansion are reduced, greatly increasing durability of the tool.