3D Model for Ceramic Slip Casting Mold

I am a ceramics maker producing slip-cast cups and need help turning my cup design into a 3D-printable plaster mold model. What I have: - A cup designed in FreeCAD - A reference model (stl only) of an existing mold showing how the frame/casing around the cup should be structured What I need: A complete, 3D-printable mold model based on my cup design, following the same frame structure as the reference. The frame should be designed so that a second cup of similar size can be fitted into the same framework in the future with minimal rework — so please build it with that modularity in mind. Deliverables: - FreeCAD source file(s) - STL files ready for 3D printing - Brief note on how to adapt the frame for a second cup design About the project: This is a small, well-defined job. I will provide all reference files at the start. The cup is a simple shape — no handles, no complex geometry. I expect this to be a few hours of work for an experienced FreeCAD user. Skills needed: FreeCAD, 3D modeling, ideally some familiarity with mold-making or casting (helpful but not required)