A modular system (1) for producing a three-dimensional object (2) by layerwise application and selective solidification of a pulverulent build material (13) contains a first module (30, 34-36; 40, 41) suitable for carrying out a first process used for the production of the three-dimensional object (2), and at least a second and a third module (30, 34-36; 40,41) suitable for carrying out a further process used for the production of the three-dimensional object (2). The first to third modules (30, 34-36; 40, 41) are configured so that the second or the third module, or both, can selectively and replaceably be connected to the first module in such a way that their housings are coupled to one another directly.