My son begs me to let him save boxes, toilet paper rolls, bottle caps, and anything else he thinks he can use to create something with. I decided to let him save some boxes and toilet paper rolls under his bed. We just break the boxes down or stack them inside of other boxes and they really don't end up taking up that much space. On rainy days I will let the kids get them out and build towers or cities out of them. The other night we took turns seeing what we could create using every box and toilet paper roll. The kids put a lot of thought into where each piece should go. They even had fun knocking down their creations. They can spend at least a few hours building cities and playing with their Fisher Price little people.