As I am studying childhood pedagogics, and I have an emphasis on media education, I am really interested on your projects.
Letting kids design products is just a amazing idea.
I also saw the thread on here about teaching kids to draw objects from different angles in order to create and print models, and am fascinated of smooth teddy 3d...
Letting kids print toys from their imagination is just something science fiction literature has not even thought about
Giving them magnetic cubes, spheres (relativly easy to reproduce in 3d) is a great idea, too.
Yeah, and besides the energy and flow that is generated when shaping with the kids, there are also two interesting side effects. One is the attitude in not just buying presents in a retail store anymore, but shaping unique items yourself. And the second one is increasing the playing lifecycle of their toys by making custom extensions. Just wait to see or next project; Zhu Zhu Pets start your engines...
Below is a picture of the prints - designed by my 7 year old daughter - that arrived today. She immediately started finishing one with the Uni Posca markers to match her favorite shirt