In MDE, design of systems can be improved and accelerated thanks to reusable models which are made available in model repositories or libraries. This paper focuses on the construction and exploitation of " o↵-the-shelf " model template bases. Model templates are parameterized models which are adaptable to various application contexts. Due to their parameterization, model templates have their own modeling space. In this paper, we present the main construction and composition operations that underlie this space while presenting its dedicated engineering processes and actors. A software environment is shown to illustrate template based engineering in Eclipse.