Use chemistry to make a bouncing polymer ball, then alter the procedure to see the effect the changes have on the characteristics of the bouncing ball.: Make a Bouncing Polymer Ball - Introduction and Materials
DIY: PVC Pipe Shoe Storage - so fun and so simple, could easily spray paint or cover in fabric or paper too. maybe a horizontal layout of two rows or something. I think this would be good for garage "yard shoes" storage
homemadecrap: DIY Garden Baskets for Storage via Centsational Girl (through Better Homes & Gardens Magazine) This I will be doing for the kiddo’s room. Garden basket storage for stuffed toys, love on a billion levels.