Virtual shop floors are used for the rapid and inexpensive development and optimisation of shop floor designs; these virtual shop floors consist of detailed simulation models of shop floor equipment/layout and a corresponding shop floor control system. This paper presents a methodology to build and integrate the specific simulation models in the virtual shop floor. The methodology extends the traditional simulation approaches by adding the necessary steps to separate the implementation of simulated equipment/layout from the control system; this separation enables the reuse of the control system in the final implementation on the shop floor, and it permits the use of the most suitable programming tools for the control software development. Moreover, the methodology integrates valuable and useful features, which are non-existent in current simulation tools. It addresses the communication aspects, timing problems, rapid development, data consistency, version control, and code reusability. The methodology is illustrated by the virtual car painting centre case of the European Mascada project. New features for current simulation packages, which facilitate the integration, are discussed at the end.