Manufacturing test structures of microsensors and microactuators is very expensive in terms of time and materials. In a conventional design process, this limits the number of design variants to be considered. For this reason, computer-supported design techniques are gaining importance in microsystems technologies. In contrast to microelectronics which may be considered two-dimensional in first approximation, a number of microoptical systems extend over three dimensions. As a consequence, a monolithic setup of such systems is not possible, as this would give rise to topological and geometric problems. Another reason for the modular concept of complex microoptical systems is the lacking of a uniform material system (in contrast to microelectronics). The modular setup of these hybrid systems results in an isolated manufacture of the individual components and their later assembly in a single system. An important aspect of construction is to ensure a certain functionality of the combined system, which is closely linked with the geometry of the structure and the application conditions. To maintain the overall function of a microsystem under the given manufacturing conditions and application environments to be expected, the system design has to be checked for interactions and adjusted accordingly. Hence, simulation of microsystems as a function of performance-reducing impacts plays a crucial role. The concept presented in this paper is the computer-aided design of a modular system on the basis of a microoptical construction kit of reusable models of fundamental microoptical elements.