Radiators of different shapes and sizes require different radiator core builder machines to suit their configurationsand dimensions. We present a design of such a machine that will be used for forming the tube-fin matrix as a part ofassembly of radiator cores. It improves upon the existing type of machine by using a single structure for the entireassembly of radiator core. Also, it can be used to assemble cores of different sizes by incorporating perpendicular linearmotion rails which can change the distance between the tube holders. This makes the machine very flexible and alsosaves time and floor space.