At Cleverly Inspired, Tracie needed an overhead projector for one of her projects. Instead of trying to find one to buy, she repurposed a cardboard box and sheet protector to become an overhead projector.
Tracie recommends using an overhead projector to help you trace words or a picture onto a wall, rather than trying to paint them free-hand. To make her projector, she cut out one side of a cardboard box, taped her printed image to the opening, and used–get this–her smart phone as a light inside the box. This setup allowed Tracie to project a phrase on the wall so that she could trace it and go over it with paint. Smart, right?
You can get more detailed instructions for creating your own projector at Cleverly Inspired.