Repairing a Surface Body to Create a Solid Body

Autodesk Fusion 360 can open STEP files directly as a solid body.  Occasionally you will find one that does not open correctly because there are faces missing and the file opens as a surface body.  This may be OK for your purpose but if you plan to modify the part, you will want to fix the missing faces and have Fusion 360 convert the part into a solid model.

I created a short video showing the theory behind this process and also demonstrated how I added the missing faces to my STEP file import to change it from a surface body into a solid body.