I teach a weekly after-school class on SketchUp at the elementary school where some of my kids go. The students range from 2nd to 5th grade. It's quite amazing to see what they come up with, after I demo a short project for them at the start of the hour.
One 5th grade girl made this Escher pattern:
(See my previous post on my video on how to create these, and other, Escher tilings.)
I thought the pattern was very nice as it was, but then noticed she added something I had to zoom in to see - the yellow face has braces on its teeth.
She's clearly mastered the multiple-copy feature of SketchUp!
Anyone can design anything in 3D! http://www.3dvinci.net/