The pantograph is basically a boom or arm of pipe with two pointers. Both pointers move together. While one pointer of the pantograph traces the surface of a sculpture model, the other point follows the pattern in space allowing the sculptor to determine the surface body of the enlarged sculpture.
The boom sits on a pivot mechanism or ball and a counter weight allows the boom to float. This helps the sculptor trace the surface of the model.
By adjusting the distance between pivot and the pointers you can calculate the size of enlarging or reduction you require. Above image shows the model on the right and armature of enlarged sculpture on left. They both sit on stable and level ball bearing tables which move together by a chain drive. The armature was created by welding pipe to a steel frame and applying a plywood base. I wanted the arms of the figure to be able to move so I attached soft 3/8" aluminum rod to the piping.
Before the advent of plastics and foam, a wood construction would be constructed for structure of the sculpture and thin wood lathing nailed to the structure. Clay would be applied directly to the lathing. If you ever see any images of these structures you would agree that the armatures were artworks in themselves.