To prepare for our project, we collect milk cartons from the cafeteria and rinse them out. After they have dried, we tape the tops closed and tape two together to make a wider house. A few years ago I discovered that it was much easier to hot glue the graham crackers to the milk carton prior to the project. That way the kids don't have to wait for the frosting to set to begin decorating. We also get pizza boxes donated by local pizza places. I cut the top off and cover it with aluminum foil. Then that sits inside the bottom of the pizza box. We always have lots of parents and grandparents who come to help. This project has become one of my favorite holiday classroom traditions.