William enlists Geoffrey and Gilbert to help him, and the three of them build the windmill. Gilbert continues to financially support the project when necessary, buying items like wire and nails. Other supplies come from the scrap heap and William’s own home, particularly the kitchen. The first piece to be assembled is the part that will take the wind energy and convert it into electricity. When he tests it using his father’s radio, there is too much power and it blows out the radio, so William makes the necessary adjustments.

Once the machine is built, their work isn’t finished. They need to craft a frame, or tower, for it to sit on. They search for and cut down trees to get the lumber they need. While they’re building the tower, a crowd assembles around them. They tease the three boys while they work. Finally, the tower and the windmill are ready. William releases the windmill’s break and the blades begin to spin. He’s holding a light bulb, which starts to glow once the current flows through the mechanism.

The community congratulates William and his family, but William’s plans to produce electricity using the windmill are not complete.