Although computer assistance for traditional animation is gaining lot of attention during recent years, it still has to cope with many limitations. Part of the current research focuses on employing full 3D input models, which are rendered and even animated in many different non-photorealistic (NPR) styles. Disadvantages are the need to create complicated 3D models and the many difficulties to achieve lively movements. Purely 2D approaches, on the other hand, need many elaborated single drawings. Getting perspective right and retaining volumes are major problem in that approach to computer assisted traditional animation, due to the complete lack of 3D information. Unfortunately, the employed software is ignorant about the approximate 3D representation in the animator?s mind. In this paper, we present novel tool for traditional animation, based on an approximate 3D model. This tool helps retaining volumes and proportions, and ensures frame-to-frame coherence.