Thanks for the response. This has been driving me nuts since I started 3d printing. Sometimes it's just as simple as wanting to put a mounting hole thru something.

I have used the mesh in Fusion, but I couldn't find it yesterday. Update moved it I guess.

I tried one - I think it was MeshMixer - a while back on an old computer, but ended up just removing it because I couldn't figure out how to use it. It's pretty obvious to me that the people who write the instructions and help for these softwares don't actually use the software. LOL.

Maybe I'll try Blender. I'm not trying to do anything complicated - just add or remove a little material - shouldn't be this hard.