This paper demonstrates the Use Case Builder tool and discusses its purpose and design. Previous results show that Use Cases can be analyzed by means of natural language processing (NLP) and rules can be defined for validating use cases against a given Ontology. By using this approach it is possible to acquire formally defined knowledge for transformation to a Computation Independent Model (CIM) in Model Driven Architecture (MDA). Use Case Builder provides a facility to define the use cases according to the integrated domain modeling approach, which is described in this paper. The goal is to provide a formal base for generating CIM with the possibility of tracing the transformation from Use Cases to the corresponding Topological Functioning Model (TFM).