Interesting project for a child A member of our hackspace wants to get their 8- and 11- year old kids1 excited about 3D-printing and CNC cutting and makering in general. We have a weekly open training where people can design and print/CNC/laser an item of their choice like a dogboned box or a two-piece sword and hilt, or a name tag, or whatever. I need a few ideas prepared so we don't spend half our lesson on Thingiverse or in Fusion (more like a quarter)! I'm not a parent and my youngest friend is probably in their twenties.

What we have: 


a full bed 1200x1800 mm CNC (preferred, because it's loud and fast)
Prusa mk3
cheapo 80W 500x300 mm laser
Fusion 360 based workflow, easy :)
Arduinos and stuff


Ideas we've had: a minecraft creeper, done as a simple-ish box.


1: the (girls) are not interested in my normal kids' goto, which is: swords, shields. They are interested in: minecraft, dragons, horses. _o_/

edit: this is NOT an opinion-gathering post, though there may be more than one "correct" answer.  We need specific applications of 3d printing for a young audience. This collection of answers will be useful to evangelize making to a whole new generation!
As @fred_dot_u mentioned above, keychains are a simple, personalized item to make.  In terms of interesting projects, things that I found intriguing when I first encountered 3D printing were objects that could not be made by other means, such as those "geared bearings" (Google: geared bearings 3d print).  Given the popularity of figet spinners a while back, they could be an interesting item.   A captive ball in a box, or three joined rings, can also be set up as a 3D print, and could have the same effect, while being easier for the kids to design. 

EDIT:  Some links to versions of items along the above lines.  Thingiverse tends to slowly break links, though, so these might not last:


Geared Bearing
Captive Ball
Three Rings
Triple Gear
Self-aligning Bushing Keychain