The process of solving a problem includes several tasks. In many situations, modeling is regarded as the key task for solving the problem. The modeling task includes an important sub-task namely model representation. Model representation results into a specification that can be communicated to the participants and serves as the basis for discussion in further tasks of the process. The modeling and its related tasks such as accreditation, verification, validation, and design for tests and experimentation require the participants to meet. It is understood that these meetings are time consuming and expensive. This paper proposes a collaborative tool to help the modelers to represent the model. The tool considers that the model can be represented using hierarchical graphs. The tool is based on a collaborative computer system named groupware and uses the concept of full replication. We show some examples to illustrate the use of the tool and we discuss some issues related to collaborative tools such as concurrency control, awareness, and performance.