- Shoe box
- Magnifying glass
- Black tape
- Thick card
- 2 rubber bands
Cut a hole in one end of the shoe box and cover with the magnifying glass. Use tape to ensure light will only enter the box through this lens.
To find the focus, point the lens at a nearby window or light source. Move the card through the box until it displays the external image sharply.
Wrap the rubber bands around the card to make a phone holder. Tape the card upright at the focus point you just identified.
Secure the phone upside down (its image will be flipped). Finally, adjust the box's position until it throws a picture onto the wall.