If you're building a toy mousetrap racer, rubber band car or rocket car–wheels are a priority–unless you're designing a car that doesn't move. Fortunately, there's a number of alternatives for making toy wheels, all made from simple and easy-to-find household objects. Cars need at least three wheels to get rolling, but you don't have to make them from the same material. And there are ways to make the wheels stronger or increase traction.
Place the mouth of a drinking glass on the cardboard and trace around the edge of the glass with a marker.
Trace the glass a few more times, one for each wheel you need. To make sturdier wheels, trace double the number of wheel patterns on the cardboard.
Locate the center of each traced circle using the ruler. Draw across the diameter of the design three or four times, and locate the center at the points where they cross.
Cut out each of the circles. Make sure that you traced the circles evenly so that the car rolls as smoothly as possible. Ream out the centers of the circles so there's room for the axles. If you've cut out eight circles, glue pairs of them together and cut them smooth.
Push sink washers into the center holes of the wheels.
Draw cut lines on the CD, if you have a Dremel tool or electrical saw use it to cut excess CD material without cracking or damaging it. Draw a concentric circle 1/2 inch in from the edge of the CD, and draw another circle 1/2 inch from the edge of the center hole. Connect the two circles with three or four 1/2 inch wide spokes--lines that connect the inner circle to the outer.
Cut out the cut lines, if you have the tools to do so. Use the hand saw to trace the lines drawn, looking from the top of the CD. To make more precise cuts, you may want to start in the middle of a removable section, then work your way outward.
Stretch an elastic band around the edge of the CD, so it creates a tight rim around the edge of the CD.
If your axle will accommodate them, use spools as wheels. This works especially well on cars with a tricycle design, and a wide front axle.
You can also pull the wheel off old toy cars, if they will fit on your axles. The tires from a Pinewood derby car, for example, can be an alternative.