I recently wrote in another Savvity community about my need (want) for an Apple Watch stand. I ended up using a design I found at Thingiverse. Since that wasn’t exactly what I wanted I also drew my own design of an Apple Watch stand. I wanted one a little bit sturdier, but not too chunky.
My favorite 3D design app is Shapr 3D. It takes an iPad with Apple Pencil to use it. Everything starts with 2-dimensional shapes that you “pull and push” into three dimensions. The basics are very simple, but you can make any complex object you can imagine. In little over an hour, I had a watch stand design I liked. I haven't paid for the ability to export 3D designs in high resolution, so what I design in Shapr 3D isn't good enough to send to a 3D printer. It is good enough to demonstrate an idea though. You can turn creations 360 degrees in all directions and zoom in and out to watch them from any angle.
If you pay the monthly, or yearly, fee for the pro version of Shapr 3D, you can send your designs to for instance a 3D printer. For someone like me, who does CAD mostly for fun, the in-app subscription isn't worth the cost (currently around 38 USD per month), but if I did this professionally, it would be negligible.
As a hobbyist, I would find it interesting to be able to pay a dollar or two for “tokens” (like in many games) that let me export designs in high resolution. It wouldn’t surprise me if the developers could make a decent revenue stream out of that in addition to the pro subscription. It also could be a path into the pro version as you get more skilled with everything you do and at some point, the subscription will be more beneficial.