Theoretically, you could probably create the face of the mold in Illustrator or Photoshop, then import into a cad program to "3d-ify" it. Otherwise, most CAD software should get you where you want to go. There are programs that are more suited to organic shapes though; try looking up Autodesk company, they have a whole suite of 3d software for different types of modeling.

Otherwise, I would recommend Blender or another 3D design program for organics.