Developable mechanism

[1][2] Some well-known examples of developable mechanisms include the door on the Apollo Command Module and the cargo doors on the Space Shuttle.

Origami uses developable surfaces because the paper can be assumed to not stretch.

[7] The same joints used to create lamina emergent mechanisms can be used to approximate developable surfaces[8][9] Developable surfaces are easy to manufacture[10] and are found in many applications.

The motion of developable mechanisms can be modeled using traditional kinematics formulas.

In rigid-body linkages, the shape of the rigid links does not change the motion.

Apollo Command Module door
The door on the Apollo Command Module is an example of a simple developable mechanism because it conforms to the conical exterior of the Module, it moves, and its hinge line is aligned with the ruling lines of the conical surface.
Space shuttle cargo doors
The cargo doors on the space shuttle are simple developable mechanisms because they conform to the exterior of the shuttle during liftoff, they can move, and their hinge lines are aligned with the ruling lines of the shuttle.