During the life-cycle of a project, the development team often discovers similarities among system components within the same or previous projects, with the potential for cost and time savings. We have encountered this discovery mechanism also in the telescope control system domain. The overall development effort can be dramatically reduced by reusing the different modeling artifacts like core requirements, functional design, and structural design. The paper illustrates some results, using the Active Phasing Experiment (APE) project as a case-study, where modeling is used as key technique to identify common system properties. APE is an opto-mechatronical technology demonstrator which was installed on the Very Large Telescope (VLT) at the Paranal observatory. When moving along a vertical cut from implementation to requirements we observed an increase of re-usability with increasing abstraction level requiring different approaches for capturing commonalities. An adequately tailored modeling strategy and an application framework based on state machines are used to create a repository of reusable artifacts with SysML and UML.