This paper describes Diorama Engine, a 3D directing tool for 3D computer animation. The Diorama Engine is a limited but specialized tool that focuses on ease of scene construction, camera control, and shot editing. These features allow quicker and easier creation of full-length 3D animated storyboards. Furthermore, 3D data can be passed directly to later production processes, enabling the work of a director to form a data foundation for the production process. A prototype version of our tool is tested, and the evaluation results suggest that the directing tool can be integrated into an actual production process.