My first 3D printer was a MakerGear M2. It was old, slow and clunky. I bought it in 2016 at the USA Science and Engineering Festival in DC, and my son used it anyway. We have since donated it.
Then Bambu came out with printers that were fast, largely reliable, and could print in multiple colors. I bought their flagship at the time, an X1 Carbon.
We learned Tinkercad. Since then we have designed hundreds of prints. It was something we could do together, and since neither of us really knew what we were doing, we could learn together.
He was very young, a literal child, but he can see in 3D better than I can. So he did most of the design work. I could physically work longer, so I printed.
Later, my son and my daughter both learned Autodesk Fusion, in a school class that required it.
Along the way we learned how to rebuild the printers. We learned what melted plastic on a nozzle means, what a hot end does, and how to mount more than one AMS, which needs a different adapter.
Years later, my daughter let me scan her paintings. They became the inserts for our art coasters.
One of them is the Migraine Headache coaster, painted by my daughter.
That is how it started: something we could do together.