This paper describes an approach to implementing virtual or constructive platform entity design using a component based framework architecture. The approach is being implemented as part of a research effort to develop a framework that allows a user to compose and recompose applications for a distributed modeling and simulation (M&S) environment, and to further compose applications into a reusable packaged execution environment. The purpose of the project is not to develop virtual or constructive applications but to develop the composition framework. However, some virtual and constructive platform entities are being developed as test cases for the framework. This paper focuses on the use of this experimental framework to develop these virtual or constructive platform level entities for the synthetic battlespace. It examines alternative component design and composition methods, which can be used to support a wide variety of application domains. Examples of these application domains include distributed mission training, doctrinal policy analysis within a particular theater or tactical situation, or engineering design alternative analysis of a particular system or subsystem, to name but a few examples. The paper discusses issues related to component design, storage and retrieval of components from a repository, composition of components into a complete application, and interoperability issues related to executing a composed application in a distributed M&S environment. The purpose is to provide lessons learned and information exchange for the benefit of projects that are concerned with developing virtual and constructive entities.