Opaque projectors are one of the oldest types of projection devices around. They were manufactured originally in the early to mid 1900s as inexpensive toy projectors. They were also designed to be used as an artist's enlarging device. The projectors enabled images and sketches to be transferred to canvas. The artist could then trace the projected image on the canvas and it would become a guide for the artist's painting.
Opaque projectors were the forerunners to overhead projectors. They can display photos, art work, documents, books, etc. and opaque objects by shining their light down, from above, onto the surface. An image of the object is focused onto a viewing screen by the use of a mirror and an imaging lens. These projectors use larger lenses and brighter light bulbs than overhead projectors as they have to project reflected light. The projectors have cooling fans, but make sure the heat from the projector's light doesn't damage the object you are using. Opaque projectors are still used but they aren't as popular these days. You can also get cases for these projectors. They can range in price from about $30 to $1,000.