Create a solar powered device

What can we use instead of a small DC motor, propeller, or solar panel if those are hard to find?

If you can't find a small DC motor or propeller, salvage a motor and fan blade from an old battery-powered toy and use them in steps 5–6, and if you lack a solar panel you can temporarily test the motor with a 1.5–3V battery while wiring as in steps 7–9 before buying a proper panel.

The fan doesn't spin even in bright sun—what should we check first?

Follow the instructions: tighten any loose clips on the motor terminals, make sure the propeller is pushed snugly onto the motor shaft per step 5, and re-angle the solar panel taped to the triangle stand (steps 4 and 10–11) so it points directly at the sun.

How can we adapt the steps for different ages so the child stays safe and engaged?

For preschoolers, have an adult prepare and cut the cardboard base and triangle stand while the child tapes the panel and pushes on the propeller (steps 1–5), and for older kids let them do the cutting, folding of the stand (step 3), and wiring or add a switch when connecting wires to the motor and panel (steps 6–8).

What are simple ways to improve or personalize our finished solar-powered fan?

You can decorate and reinforce the cardboard base from step 2, add a second solar panel wired in parallel to the panel taped to the triangle stand for more power, or mount the whole assembly on a lazy susan so it can rotate toward the sun.