If they are into anything mechanical or building, there are many opportunities to design functional parts and things that do stuff.
On top of that its a great opportunity to learn the connection between CAD and how things actually come out - when you screw up your design, it doesn't work.
With the A1 mini being only $200 right now, its a cheaper educational tool than almost any kind of building set, robotics kit, or anything else worth its salt.
On Makerworld there are all kinds of useful things you can quickly print yourself that are actually quite practical. Tons of tools storage things.
Last week a made a new set of rubber feet for an outside chair to replace the old ones that had worn down. Delaney printed a bunch of things for cosplay outfits, some she designed, some just downloaded. I'm designing a custom radio bezel for my 4runner right now bc the OE isn't very compatible w/ modern DIN radios. Oh I also just made a hook to hang the crank bar for our retractable awning when its not it use.
Again, for a couple hundred bucks - you could view it like any tool. Maybe you'll only use it a couple of times and spend a lot of time sitting but the times you need it, very handy.
And Bambu is really idiot-proof. IMO perfect for kids bc you don't have to do anything w/ the printer itself, it just works.
EDIT - he's hardly still a "kid" but Jonas just designed and built a 2 DoF turret for a nerf tommy gun with a webcam on it that autodetects people (using the YOLO AI library and OpenCV) and shoots them. Most of the mechanics of the turret are 3d printed 
