Hi!
I can help you with the modification of STL for 3D printing. I can open the 3D models in Rhino/AutoCAD and export them to Blender for a mesh analysis (non-manifold edges, inner faces, etc). I work in a 3D printer shop (we sell CubePro, Cube3, UpPlus, Witbox, Prusa, etc...) and I'm the designer that works with CAD software, polygon modeling software (Blender, 3DSMax, etc) and photogrammetry. I prepare all models for 3D printing.