A method for forming heat transfer elements of heat exchangers, said method comprising arranging a pair of rollers in a spaced manner to configure a nip, the pair of rollers rotatable along respective axes thereof, and feeding a metallic sheet through the nip between the rollers to form a heat transfer element, wherein each roller comprises: a central shaft; and a plurality of roller elements, each defining an outer periphery, each roller element comprising a geometrical characteristic configured across the outer periphery thereof, the plurality of roller elements adapted to be stacked on the central shaft, the stacked roller elements on the central shaft configures the roller with a circumferential surface corresponding to the geometrical characteristic of the stacked roller elements, to form the heat transfer elements corresponding to the circumferential surface, wherein each roller element comprises a cutout, defining an inner periphery opposite to the outer periphery, through which each roller element is stacked on the central shaft; wherein each roller element is a thin metallic sheet, cut by one of a laser cutting process or a water-jet cutting process, each geometrical characteristic comprises a combination of undulation sections, corrugation sections, flat sections, notch sections, rib sections, tab sections, dimple sections and a ripples section; wherein the roller further comprises an engaging arrangement to enable stacking of the plurality of roller elements on the central shaft, wherein the engaging arrangement comprises: an engaging member extending longitudinally on a surface of the central shaft; and a complementary engaging member extending downwardly from the inner periphery of each roller element to match the engaging member to stack the plurality of roller elements on the central shaft. a central shaft; and a plurality of roller elements, each defining an outer periphery, each roller element comprising a geometrical characteristic configured across the outer periphery thereof, the plurality of roller elements adapted to be stacked on the central shaft, the stacked roller elements on the central shaft configures the roller with a circumferential surface corresponding to the geometrical characteristic of the stacked roller elements, to form the heat transfer elements corresponding to the circumferential surface, wherein each roller element comprises a cutout, defining an inner periphery opposite to the outer periphery, through which each roller element is stacked on the central shaft; wherein each roller element is a thin metallic sheet, cut by one of a laser cutting process or a water-jet cutting process, each geometrical characteristic comprises a combination of undulation sections, corrugation sections, flat sections, notch sections, rib sections, tab sections, dimple sections and a ripples section; wherein the roller further comprises an engaging arrangement to enable stacking of the plurality of roller elements on the central shaft, wherein the engaging arrangement comprises: an engaging member extending longitudinally on a surface of the central shaft; and a complementary engaging member extending downwardly from the inner periphery of each roller element to match the engaging member to stack the plurality of roller elements on the central shaft. each roller element is a thin metallic sheet, cut by one of a laser cutting process or a water-jet cutting process, each geometrical characteristic comprises a combination of undulation sections, corrugation sections, flat sections, notch sections, rib sections, tab sections, dimple sections and a ripples section; wherein the roller further comprises an engaging arrangement to enable stacking of the plurality of roller elements on the central shaft, wherein the engaging arrangement comprises: an engaging member extending longitudinally on a surface of the central shaft; and a complementary engaging member extending downwardly from the inner periphery of each roller element to match the engaging member to stack the plurality of roller elements on the central shaft. an engaging member extending longitudinally on a surface of the central shaft; and a complementary engaging member extending downwardly from the inner periphery of each roller element to match the engaging member to stack the plurality of roller elements on the central shaft.