Modify Head Scan into Precision Two Part Mold (STL/CAD)

I am looking for an experienced CAD/mesh engineer to modify an existing 3D head scan and STL into a production-quality two-part mold for casting a hydrogel head cap. The primary task is to create a smooth, watertight inner core that preserves the overall shape and proportions of the head while removing facial features, ears, neck, and other unnecessary anatomy. The inner core should provide a nominal **0.125-inch clearance** from the original head scan over most of the surface, increasing only where necessary and generally not exceeding **0.25 inch**. Once the inner core is finalized, create the matching outer mold STL with the specified wall thickness and manufacturing features. The finished deliverables should include printable, watertight STL files for both the inner core and outer mold, along with the native CAD/source files. The outer mold must be designed around the finalized inner core so that the inner core fits correctly inside it with the intended casting cavity and adequate manufacturing tolerances. I will provide the original head scan, the current inner and outer mold STLs, dimensional requirements, and previous measurement reports to minimize engineering time and cost.