How to keep a child busy for hours in the summer: DIY: Giant Ice Cube Awesomeness - filled with plastic animals, dinos, and such. And I'm sure you could put in food dye before its frozen to color it like the ice block in the photo.
How to Make a Tire Rocker. Here's a cute way to recycle those old tires in your garage, Build your kid a rocker for him to enjoy! Find yourself an old tire, clean it very well and measure and find it's center.