Here's an easy one to keep your kid occupied. Inspired by a picture I saw on Pinterest, we put this together on Sunday. I think the picture is pretty self-explanatory. We kept ours very simple, using paper towel rolls glued onto a flat piece of cardboard. We tested out lots of different things - balls, cars, trains - but the balls (bouncy or otherwise) worked the best. We did have to make a few modifications - added a couple guardrails, etc - but I think that was the best part. The trial and error, figuring out how to make it work better. A fun and super easy activity!