Build a cardboard vehicle

What can I use instead of wooden skewers, drinking straws, or bottle caps if they are hard to find?

Use chopsticks or thin wooden dowels instead of skewers, cut sections of a pen barrel or sturdy craft straws to tape under the chassis in place of the drinking straws, and substitute large buttons, toy wheels, or jar lids for the bottle caps when making the axle assemblies.

Why won't my wheels spin freely and how can I fix it?

If wheels stick, check that the straws taped to the underside of the chassis are straight and not pinching the skewers, widen the holes in the bottle caps slightly and sand or trim skewer ends, and secure each wheel with a small tape wrap placed just outside the caps so they can't slide but can still rotate.

How can I adapt this cardboard vehicle activity for younger children or older kids?

For younger kids have an adult cut the 15 cm × 8 cm chassis and pre-thread axles using large buttons or toy wheels for safety, while older children can trim skewers to custom lengths, add aerodynamic spoilers from extra cardboard, and measure roll distances to compare designs.

How can we make the vehicle go farther or personalize its look beyond the basic decoration step?

To improve distance swap to larger or lighter wheels (replace bottle caps), reduce axle friction by using smooth pen-barrel sleeves instead of straws, add a rubber-band motor or adjustable cardboard spoiler, and decorate with extra cardboard pieces to personalize as described in the decoration step.