Surface Model To Editable Solid

I have a product model that currently exists only as surface geometry; I can supply it to you either as a STEP file or the native, imported SolidWorks file. What I need back is a clean, fully-defined SolidWorks part in which the geometry is rebuilt as true solid bodies—not just knitted surfaces... (Budget: $30 - $250 USD, Jobs: 3D CAD, 3D Design, 3D Drafting, 3D Modelling, Solidworks)