I am looking for ways to import large STL files into SolidWorks as solids, not just surfaces. I've attached a model of a bone as an example. I want to modify it with clean CAD geometry then export it to a 3D printer.
Check this link:
I hope it will be good solutions.
I was able to create a solid CAD model of your .stl file. See the attached PDF for a screenshot of the part in Solidworks 2017. Not sure if this is exactly what you were looking for. The part shown in the screenshot is in a .step format. Some of the detail on the inner orbital sockets of the skull were lost due to the .stl having to be completely manifold before surfacing but most of the detail overall remains intact.
Attachments3D_BONE.pdf, 431 KB