Make your own DIY overhead projector for tracing wall murals. Make a makeshift projector using a box, a lamp and some tape. Project the transparency onto the wall. Use a light bulb without the "frosting" on the inside for a clearer picture.
When we hear about overhead projectors, we tend to remember the old transparency projectors used in schools and business meetings back in the days. With the new and improved designs in projectors, some people have come to regard overhead.