For a documentary on James Eads, an American engineer, a miniature diving bell was constructed. This section on the PBS Web site talks about the process of shooting models with cinematographer Boyd Estus.
"Art Director Katha Seidman created a six-inch high model of Eads' diving bell using basswood, lead fishing weights, copper wire and a fish tank hose. The shot of the diving bell from below was achieved by shooting the reflection of the model in a mirror as the model was lowered into a water tank. The camera was on the outside of the tank. The mirror was positioned on the bottom of the tank at a 25-degree angle to the floor."
American Experience: Behind the Scenes