In micro production high lot sizes, which are required for cost-effectiveness, are often not achieved, e.g. due to a high number of product variants or limited demand. Therefore new approaches for production like changeable manufacturing systems are demanded. In this paper a concept for a modular workpiece carrier system including a platform for sensors and actors is presented. The modular design allows the easy adaption of the manufacturing system to new products by the workpiece carrier system in terms of hardware and even the integration of additional process functionality.