My sister-in-law has more energy than anyone I know. Her latest project is Tire World. Her friends had 4 tractor tires that they had no use for, so my sister-in-law jumped at the chance to take them. It took 3 people to roll each tire down the street to her house. These are huge tires. She and her husband made a pit filled with pea gravel for the tires to sit on. They built ladders and a window to finish off the play area. Her kids love it. I think it’s pretty darn cool.