Abstract: A collimator for radiation receiving and imaging devices and a method for making such collimators including the steps of forming a plurality of modular elements each comprising a foil sheet bent so as to form a plurality of elongated ridges on both sides thereof so as to form elongated channels therebetween, partially inserting the ridges of one module into the channels on the adjacent side of the succeeding module in a modified mortis-tenon relationship successively and affixing them in that position, placing the assembled grid into a frame, and filling the spaces between the grid and the frame with radiation-opaque material, thereby forming an integral functional collimating unit.