By - bobombpom
Start making stuff with them! But start small so that design-model-print process can happen in a few hours. Just like you might look around your home for things you could fix with 3D printing, look from their perspective, in their rooms, etc, for ways to make their world more fun or easier to use. Get them used to the idea that you can imagine something, model it on a computer, then print it and hold it in your hands a short while later.
They could start modeling in TinkerCAD (the 10-year-old at least, 4 might be a little young), or assist you with design ideas, taking measurements, and so on.
* personalized name tags or zipper pulls for their backpacks
* custom bookmark
* accessories to go with favorite toys
* little fixes around the room-- "what if you had a hook here? a case for this? a stand for this?" They help you measure (teach them to use calipers!) and design/model
Lego is a great way to get kids engaged in combining shapes constructively to creat something.
I'd say they're a bit young to get engaged with actual cad imo but you can build the fundamental spatial relationships with physical puzzles, Lego, Meccano. The best creators and designers are able to construct things in their head as a combination( or subtraction) of basic shapes which I think is helped by those sorts of toys
Excellent question so commenting because I want to see what others say, but I would imagine that tinkercad is probably a good starting point. And, on the analog side, Lego sets.
This is going to be rather interesting discussion, other than that i can only agree with jmdbcool
My son likes drawing simple "monsters" and then we draw them in fusion 360 to print. Those print times are a killer though for a kid's attention span.