Abstract: The present invention relates to a method and a fixture system for providing a fixture for the positioning and clamping of details to be assembled, preferably by welding. According to the method drawing information for the assembled product is provided in a computer program, a zero position on the product is established, an installation plan for the fixture to be built is provided by determining support positions in a system of coordinates, for the fixture relative to the product, based on the drawing information and starting from the zero position on the product, and the fixture is built up according to the established installation plan and from standard fixture components (1, 5, 7, 14) selectively interconnectable by means of hole systems (2, 6, 18, 15) extendable along the X-, Y- and/or Z-axes of the coordinate system.