Google or search the forum for "jewelry casting techniques" I think that will be your best option.
It probably involves making a rubber negative mold from your positive master.
Then cast wax positives in the rubber mold, and use those wax positives to make high detail molds in heat proof plaster. The wax enables you to make a high detail mold then melt the wax out without damaging the mold detail.
Then obviously cast metal in the plaster mold and destroy the mold to release the metal.
Another option would be to machine a female mold direct from steel, provided it has no undercuts. The cast a lower temperature metal product in the re-usable steel mold. But that requires a lot more mold costs and your clay master is not able to be used.