The assembly steps are as follows:

1. Cut the pumpkin and remove the fibers and seeds inside, leaving a flat surface.

2. Place the pumpkin on a stable surface. You can use some supports to keep it stable. Place the small ball (representing the moon) on a cutout of the pumpkin so that it is in the center of the pumpkin. .

3. Use a lighter or candle to light it, and place it on another cutout of the pumpkin to make it a light source simulating the sun. Adjust the position of the moon model so that it casts a shadow on the surface of the pumpkin. Above, you'll see an eclipse-like phenomenon, with shadows covering part of the pumpkin.

4. You can use colored paper or colored pens to draw some patterns on the surface of the pumpkin to increase the visual effect.