Have your kids turn a handful of office supplies into a busy fleet of cars and trucks.
Begin by cutting erasers with a knife (a parent's job; kids can use scissors for this, but the cuts won't be as straight).
Stack the erasers to make cars, trucks, and trailers. Pencil-cap erasers and automatic pencil eraser refills make good cargo. Use white glue to hold the pieces together.
To make tires, press thumbtacks into a piece of cardboard, color them with permanent markers, then remove the tacks and press them in place on the vehicles.