Science/Small Manip - Creative "racetrack" for cars. Creates a secure platform for children to race cars down the ramps. Children could extend this to use different items (balls, blocks, marbles) to see how quickly different objects roll down the ramps.
If you're looking for some easy crafts with toilet paper rolls and egg cartons, you'll love this simple airplane craft idea for kids. A plane and pilot-Crafts with toilet paper rolls - crafts with egg cartons