Process for the realization of counter-mould elements for the containment of welding bead of plastic profiled elements, in which counter-mould elements (1) have a main body (2) adapted to receive in abutment a pair of profiled elements of plastic material welded together to obtain a frame for windows/doors, each profiled element comprising a welding surface weldable to the welding surface of another profiled element in a welding configuration in which the lateral faces of profiled elements are substantially adjacent to one another and define a locator surface, wherein the process comprises: aphase of acquisition of the profile of a portion of the lateral faces; a phase of definition of the profile of a contact surface (3) of the main body (2) adapted to receive in abutment the locator surface, the profile of the contact surface (3) being substantially complementary to the profile of the locator surface; a phase of three-dimensional molding obtained by means of a three- dimensional molding device (4) to obtain the main body (2) starting from the profile of the contact surface (3) obtained in the phase of definition.