Showcased here is an unpainted Martian Manhunter hardcopy. The piece is cast in a green urethane, commonly referred to as "dynacast". This material was prominently used for hardcopies during the mid-80's.
Hardcopies are produced using a silicone mold (this mold is created from the orginal wax figure sculpting). Once the hardcopy is removed from the mold it may serve a number of purposes. It might remain unpainted and ultimately used to create the steel tooling for the figures. Extra hardcopies are poured as a precaution, should something happen to the tooling master. These extras would remain unpainted as well. If a hardcopy is not destined for tooling or backup, then it will more than likely be handpainted for use in catalog photography, trade shows, or as a paintmaster. Most paintmasters for the Super Powers line are cast in milky white proto plastic (commonly referred to as internal first shots), but I have seen dynacast paintmasters.
Above you can see the figure in its unassembled state. Kenner utilized metal dowels to attach the limbs and head to the torso. This hardcopy, like all others, is slightly larger in size than the production counterpart as the resin does not shrink like injection molded plastic.