Postive mold into a Negaive mold.

I'm looking for a Solidworks, Fusion360, Inventor Pro Professional to create a NEGATIVE mold from a positive .STL file. The Negative mold will be 3D printed and used to create a POSITIVE mold, so the finished CAD model of the negative mold should be SUPER SMOOTH. This should be quick work, converting a MESH file into a solid body and used to create a cavity block in Solidworks etc, etc.