A customizable and extensible tool is proposed to implement ModelGen, the model management operator that translates a schema from one model to another. A wide family of models is handled, by using a metamodel in which models can be succinctly and precisely described. The approach is novel because the tool exposes the dictionary that stores models, schemas, and the rules used to implement translations. In this way, the transformations can be customized and the tool can be easily extended.