When designing their own interactive 3D worlds and computer games, children can not only engage in a fun and playful activity that has meaning to them, but will be able to strengthen their creative power as well as their analytical and problem solving skills. However, this requires tools that are designed carefully to foster these processes and to be fun to use at the same time.

We present work in progress on designing a 3D authoring tool for children to create interactive 3D worlds. In the design process, emphasis was placed on fostering the user?s creative process as well as on conveying mathematical and structural principles and ways of thinking through the tool?s structure. In the design process of a 3D authoring tool, these two goals often stand in contradiction to each other. In this paper, we discuss selected problems that are characteristic to the design of this authoring tool and present our solutions to these problems as well as the resulting preliminary prototype system JiVE.