Double check that the plastic box is secure with no space for light to enter in. Prepare black paint in a bucket and apply it to the inside of the box, so that light cannot enter inside the chamber in any way.
Use a ruler to measure 3 inches from the bottom of the box and mark it with a pencil. Make a 1 / 2 inch hole at the marked spot with the help of a utility knife. Cut a piece of foil to cover the hole that you have just made. Paint the outside of the box black - use spray paint for a good deposit.
Give the paint about 15 minutes to dry out completely. The next step is extremely delicate and requires great focus. You will have to cut a hole in the aluminium foil, but it has to be of the perfect shape and size. The smaller the hole size, the better the focus of your camera.
Cut a small rectangle of 3 by 5 inches out of the black construction paper and fix it next to the hole with the help of the tape. You should be able to cover or uncover the hole by sliding it over the front side of the camera. Practice on moving the paper back and forth as you will be using it to vary the exposure time.
Cover the hole for now and enter into a room with pitch black darkness. Arrange a red torch for your vision as all other light colours will damage the photographic paper and ruin the picture.
Put a photographic paper inside the plastic box so that its active surface faces the pinhole. Close the lid and seal the compartment tightly so that no light gets through.