Abstract: The invention relates to a method of accurately joining together two sheet sections along edges of the sheets having complementary shapes, and wherein the edge of at least one sheet section is formed by means of a numerically controlled machine with the sheet section fixed in a fixture by moving a cutting member relative to the sheet section according to a predetermined path, whereafter complementary edges of the two sheet sections are made to abut each other and the two sheet sections are welded together in a numerically controlled machine, one sheet section being fixedly retained in said fixture and the knowlegde of the path used during cutting is used to determine the path of the welding means at the welding of the sheet sections.