This is a remix of the NASA Pinhole viewer While they have a 5 mm hole for viewing, they also have an activity where you can see the eclipse through holes and shapes of different size. This has a 10 mm, 7 mm, 5 mm, 3 mm and 1 mm hole. It also has a star, square, triangle, and heart shaped hole. This will let you see if the shape of the opening affects the shape of the eclipse! A full lesson plan is avalaible on TPT,