How to make a pinhole camera with shoe box

1Create two openings. On one of the box’s smaller sides, use a pin or needle to punch a round hole that is roughly 0.8 inches (2 mm) in diameter  in the center of the box’s side. On the box’s other small end, use a pen or pencil to trace a rectangle with a border of about a half-inch to an 1” (1.27 to 2.54 cm) between the edge of the outline and the edge of the box on all sides. Use a utility blade to cut along the outline.
2.Create a frame for a screen. First, measure the inside dimensions of the shoebox’s smaller ends. Use a pen or pencil to trace an outline of these dimensions on a sheet of cardboard with the help of a ruler. Use a utility blade to cut along the outline. Slide the cardboard cutout into the shoebox, covering the larger opening. Use a pen or pencil to trace the outline of the opening on the cardboard inside the box. Remove the cutout and cut along the new outline to create your frame.
33Add a translucent screen. Lay your cardboard frame on top of a sheet of translucent plastic. Trace the outside of the frame on the plastic with a pen or marker. Remove the frame and use scissors to cut out the plastic. Lay the plastic cutout over the cardboard frame and staple them together along each side of the frame. Insert your screen inside the shoebox once you are finished so that it covers the large opening.[3]A plastic shopping bag will suffice as cheap, ready-at-hand material for your screen.4Demonstrate your camera. Set your shoebox camera on a flat surface. Aim the pinhole end at a well-lighted object. Cover the shoebox with a large black cloth. Pull the cloth black to uncover the pinhole. Drape the cloth protruding from the other end over your head. Block out as much ambient light as possible so you can see the well-lighted object projected through the pinhole onto the translucent screen inside your shoebox.[4]This is a very basic device, so even objects that are well lit still appear only very dimly on your screen. However, it still demonstrates the basic principle of how an analog camera captures images on film if you use your hand as a shutter.
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The answer is 18

Explanation: