Have you ever left clothing or colored paper out in the sunlight?
I once left a dark blue skirt on the backseat of my car for several weeks (yes, I know, I should clean out my car more often). When I finally did take it out, I found that it had literally been tie died by the sun! This same principle works with paper, and can be used to create interesting silhouette artwork. Start by collecting your materials: construction paper (dark colors work best) and an array of interestingly shaped objects from nature (leaves, pine cones, sticks, rocks, etc.). Place your paper in a sunny spot and place the objects from nature on it in any arrangement that you think will be interesting. Leave the paper and objects for a few hours (the sun has to be bright!) and return to see the shapes that have been created. You can also purchase beads and even hair clips that have photosensitive chemicals in them that change colors when exposed to direct sunlight.
There’s a lot of power in sunlight. Have fun experimenting!