Thumbtack (or earring)
White strip of paper (optional)
Recommendations: In some cases, especially if you are doing with kids, you might want to reinforce the “blocked hole” (the one with aluminum foil) with stronger tape. Some types of aluminum foils might easily rupture.
Some people might place a strip of white paper taped on the bottom inside of the box. This way the eclipse could be projector and viewed better in some cases. This is optional. If done, should be the first step of the project.
You are all ready for the eclipse. You can test this by putting your back to a lamp or flashlight and looking through the opening. You will see how the light coming though the small pinhole will project at the end of the box. When the eclipse is occurring, you will see how the circle becomes crescent.