How do I create a mating part from a part file generated from 3D scan?

I've scanned a circular part body for the purpose of creating some mating parts.

I have the scanned part file in IGES and STEP formats and opened and imported in SolidWorks 2016.

How do I model the inverse of the body shape so that I can create an exact match of certain areas?

I would like to 1) to design a part that will insert and mate perfectly into a specific cavity on the original, 2) to create a cover for the part that matches the contour of the body.

I'm using SolidWorks2016 Student Version.

Is this possible with this version, and if yes, can someone point me in the right direction?

Thanks