I have used the cavity feature in the past, but am having issues this time around because I am working with files not native to SW (no tree). I am running SW 2017 Professional. Someone sent me a stp file of a part. I need to edit it and create the mold via the cavity feature.

They have several extruded cuts that I need to fill in, since I don't want those features translated into the mold. I have "filled in" the extruded cuts three different ways, but when I use the cavity feature they still show up in the mold. How do I get my newly created surfaces to translate to the cavity?

I have tried Extend Surface, Extrude Surface & creating new sketch and revolving a new solid. Visually, my edited solid looks the way I want it to. But once I apply the cavity feature, the original extruded cuts are back (not filled in).

Thoughts?