You may not be able to put a square peg in a round hole—but you can make a square wheel roll on a round road.Square wheels roll smoothly on a surface with bumps of the right size and shape.
- About 20 cardboard toilet paper tubes (all approximately the same diameter)
- Foamboard, stiff cardboard, or matboard to serve as a base for the cardboard tubes, about 4 x 30 inches (10 x 75 cm)
- Hot-glue gun and glue sticks
- Poster board or matboard, approximately 8 x 10 inches (20 x 25 cm)
- Pencil or pen
- Drinking straw
- Two bamboo skewers
- Paper clip
- String, about 12 inches (30 cm)
Using hot glue, attach a cardboard tube across one end of the base. Continue gluing on tubes, with each tube just touching the one before it, until you reach the other end of the base (see photo below).
Measure the diameter of three or four of the toilet-paper rolls. The diameters should be approximately 1 11/16 inches (4.3 cm). If this is the case, cut four square wheels from the poster board, with sides of 2 inches (5 cm). If the diameter of your tubes is significantly different from this measurement, then make the sides of the square wheels equal to 1.2 times that diameter. (See the Math Root below.)
Use the pushpin to poke a small hole in the center of each square wheel, taking care not to bend or crease the wheel.
From the poster board, cut a rectangle measuring 2 x 5 inches (5 x 12 cm).
Cut two sections of straw, each 2 inches (5 cm) long.
Cut the skewers into two 5-inch-long (12-cm) pieces, each with a point at one end. These will be axles. (If you can’t cut the skewers with the scissors, just break the skewers, or cut them with a utility knife.)