I find knoowingbthe basics helps.

I use blender. Its not perfect for 3d modeling. But I knew it a little to start. Also easy to set up on linux.

But honeatly learning its scale odds. (Defaults 1m to mm) boolean modifiers and 3d print tools. (Allow testing for real world models and extra faces.)

Really is all i need to modify stls and make my own sruff.

i've been dying to try an llm that can generate stls from natural speech

Netfabb before Autodesk fucked it will fix a lot of hanging vectors, Sketchup is just way easier to use than any CAD software I've every used but may or may not be able to open files included with Thingiverse downloads, depending on what was used to make them.

DM me if you need a copy of either. I've installed both on Linux in the past as well and have a link to some documentation on that.

@Krauerking my opinion is no. For many things you can find a model on line. Much of the challenge can be getting the printer to work as you wish, so modelling might not be first on the to do list.