I would encourage people who have never designed physical objects before to try to only print things they have designed themselves as an exercise. For perhaps a year or so.

If you have never designed physical objects before it is really challenging at first. The learning curve is pretty steep and, at least in my case, I discovered that I didn't have a mental language for thinking about functional 3D and mechanical design. You also start to look more closely at the objects around you and think about what went into designing them.

I started doing 3D design about a decade ago, when I got my first 3D printer. At first using free modeling in CAD and then later learning how to do constraint based and parametric designs in Fusion 360. This felt slow and perhaps limiting at first, but when you get used to it, it will save you a lot of time later and allow you to make more useful designs that are much easier to evolve and vary.

I think it took something like 4-5 years before I printed something someone else had designed. Mostly because I used 3D printing to make custom parts for my own projects, but also in an effort to force myself to learn. I know the learning curve was steep, but for some reason I have forgotten how much work it was to learn.

Now there are so many useful designs, designed by people who are a lot better than me available everywhere that I do print a lot of things others have designed. But I think learning to design things yourself is a really good opportunity to learn useful skills.

For instance, I had never anticipated that I, a software engineer, would get paid, by an actual customer, to design parts for their projects. Or even consult on physical design for someone doing product development. I am by no means at the level where I'd put it front and center on a resume, but I can design, and to some degree, manufacture simple mechanical parts.

(Along with 3D printing I've been doing some CNC at a very hobbyist level. I would still say I am very much a beginner when it comes to machining metals, but it is really fun to see that you can make reasonably precise metal parts for real applications (car parts) at home in my garage with not that much effort. This weekend I'll be doing thread milling in aluminum for the first time on a part that requires M3 screws)

I echo this sentiment. So many random annoyances around the house that I've fixed with self designed prints. Its a steep learning curve but you can start simple. First thing I designed was a spacer to go behind silverware organizers to keep them from sliding around. Still in use almost 8 years later. Horrible print quality and all.

Last year I printed a peg leg for a nonstandard luggage wheel that broke off my suitcase and Samsonite won't sent a replacement for, a cleanable coil denitrifier for a saltwater aquarium, custom shadowbox drawer organizers for a toolbox, and during an aquarium emergency printed a metric to US pipe bushing.

I also put the skills to use for woodworking modeling a set of couch doggie stairs and a couple years ago designing the building for my observatory.

It's a really really useful skill

I will add that FreeCAD has come a long way in constraint based and parametric part design, and I'm able to use it exclusively running an Arch-based distro.

Deltahedra has extremely impressive tutorials on YouTube. No fluff -- no long intros or filler -- 30-60 minutes of dense content, clearly explained: https://www.youtube.com/@deltahedra3D

Since I'm a developer with no experience in 3D design, I just automated my process with freecad and vibe-code my models with GitHub copilot. That gives me instant visual feedback plus 3d model code I can check in into git: https://github.com/micw/freecad-automation

3D printing has been humbling for me.

I can express myself well spatially in code, but that doesn't help much in CAD where you have to figure out what combination of buttons and parameters will do what I want.

I can manage dependencies well in code, but that doesn't help much in CAD. I continually struggle to design parts with geometry that is dependent on the spatial relationships and constraints of how multiple parts connect together.

I print a lot of stuff I design, but I am not very good at it.

But a heck of a lot of what I print doesn't exist, or only exists in disparate parts. So I am forced to RAD a lot of stuff together.

I don't do this because I don't have the time to design wargaming terrain, but I've definitely pushed myself to do more designing for household things.

It's a really good feeling to be able to put something together that solves your problem. As I asked my wife, "Is this why people with wood shops are always so smug?"

It's also fun to be able to feel your skills building. I now have opinions on friction fit box lids.

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.