The CRECON multifunctional modular system is a set of structural adapters (connectors, reducers and accessories) designed for a series of steel profiles and wooden beams, which allow to build demountable structures of different shapes and sizes for any application and at the same time facilitate the assembly of structures as it eliminates the need for carpentry joints, fusion welds, mitre cuts and other technical details performed by qualified workers. The system is based on adapters tailored to the internal dimensions of the steel profiles and to the external dimensions of the wooden beams, with holes on each side suitable for a bolt and nut (or wood screw) connection. The bolt holes are located at precise points on the sides. For each dimension of the joint (within the series) in different sizes and shapes, however, so that different adapters can be connected in as many different ways as possible. For the basic joints (rectangular joints) of all possible branching (8 possibilities), only 2 parts need to be produced in series to make different types of rectangular joints. There are 6 types of adapters (15,30,45,60,75, adjustable) for the angled joints, which make it possible to construct an angled joint with different angles.