You can get pretty quickly at it with Blender instead of proper CAD. Just do the "donut tutorial", set the correct workspace dimensions and go for it. You can learn basic modelling in a day.

Blender is overwhelming at first glance, but it becomes incredibly intuitive once the UI clicks. Of course modelling for printing in Blender has drawbacks and limitations. It's more fiddly, but unless you are super stupid, you can get pretty far, pretty quickly. And you can do sculpting and organic shapes, which are hard/impossible in CAD. Learning Blender basics is worth it anyway, incredibly useful for thinking and sketching in 3D. Oh, and it's FOSS, runs entirely locally, doesn't spy on you, or appropriates your creations like the "free" Fusion360 and their forced cloud crap.

Once you got annoyed by Blender's limitations for 3D printing, you can learn CAD. But Blender is the best way to get into it IMO. Trust me, you won't regret learning Blender basics, in any case. It's expanding your creative horizon and is fantastic, very pleasant software.

I second Blender. I don't use anything else and don't see why I would want to. I hope to get into geometry nodes in future.

The donut tutorial is .. handwavy relevant to 3D printing.

3D modelling for 3D printing doesn't require materials, colours, lighting, camera placement etc etc. But doing the donut tutorial will get you used to many aspects of blender and realise just how powerful this software is. It's also kind of a Blender right-of-passage.

The Blender documentation is fantastic if you prefer to learn via pages than random video-build-a-thing tutorials.

Blender tends towards using keyboard shortcuts. Learning them can greatly speed things up.

And Blender has a large body of community forums for questions and answers if you want to search(first), post a question, or likely ask your friendly AI what the answer is.

[edit] the bite sized blender basics videos on the blender.org site no longer easy to find. :-(