What is more fun than making a robot that can draw? I don't know, but kids will spend hours crafting the perfect creation that can dance and wiggle while drawing! I recently did this project with 3rd through 6th graders, and it was a blast!
Here is one set of directions by DiscoverE. It says for k-5, but I have made them with my high schoolers as a design challenge, and they have loved it. Challenge examples: Scribble the biggest circle, smallest circle, straightest line, farthest distance, fewest contact points....
And another example of directions by the Exploratorium.
This is a great place to use recyclables and all that random GAK (generally awesome krud!) you have lying around!