Component based or building block based simulation model development is regularly mentioned as an interesting new development and a potential field of research. Most of the commercial simulation environments offer the users of their software functions to group model constructs and upgrade these to advanced model constructs that the users can use in future simulation studies. Unfortunately, the created model constructs are rarely reused and often stop being used after the first simulation study. In this paper we describe a list of guidelines to consider in the design of building blocks to enhance the reusability and the flexibility of the simulation building block to be used in multiple simulation studies, also by model developers who have not been involved in the design of the building blocks.