How to Build a Cardboard Marble Run

Learn how to engineer a custom marble maze using recycled cardboard and basic household supplies. HowTo: Family Edition: family how-tos that actually help.

1. Prepare your track pieces. Cut your paper towel rolls in half lengthwise to create U-shaped tracks. Use your scissors to cut flat cardboard into long strips that can serve as walls or ramps. Ask a grown-up if the cardboard is too thick to cut easily.
2. Create a base. Find a large, flat piece of cardboard or use the side of a box as your main wall. Lean it against a chair or wall so it stands upright. This is the 'canvas' where your marble run will live.
3. Attach your ramps. Tape your track pieces onto the base at an angle. Start at the top and work your way down. Test the slope with your marble as you go to make sure it rolls smoothly without getting stuck.
4. Add obstacles and turns. Use small bits of cardboard to create bumpers or funnels. If you want a spiral, try curving a piece of cardboard and taping it firmly to the base.