I'm trying to do something that feels like it should be simple, but I'm struggling to find a way. I have an stl file that has spots for two items and I wanted to reconfigure it to only have one spot. I just want to cut and merge but this seems impossible. Any suggestion on tool and how to do this?

What software are you using? Do you have any experience using any CAD-program?

Try blender. YouTube tutorial.

If you just want a straight cut I'd think your slicer would be able to do that. Prusaslicer can, at least.

Tinkercad. Paste it in twice. Edit away half of each, stick together.

That is s fun little tool. Worked great, thanks!

After doing it in TinkerCad, it does look like the slicer could probably have done it too. Thanks!

MeshMixer is the program I use for a lot of mesh editing. It has a nice set of features, but feature development was ended in 2021, so there may be more modern options available.

I've tried Blender and continue to try to learn but it has an insane learning curve. Imo, it's only useful for artistic work.

I really need to learn it. I bought a 3D scanner (Raptor Pro) that does good scans, but it turned out not to be that useful since I can't really edit the output meshes in Fusion.