Method for producing a corner element or a connection element (1; 1') suitable to mutually connect a plurality of tubular elements making up a structure, comprising the following operations: - providing a shaped laminar body (3; 3') in a material suitable for being plastically deformed; - bending said shaped laminar body (3; 3') along three bending lines (4, 5, 6) converging in an intersection point to delimit three corresponding portions (17, 18, 19) of said shaped laminar body (3; 3'), so as to define corresponding concave areas (7, 8, 9) suitable for housing said tubular elements; - making in said shaped laminar body (3; 3') two cuts (4a, 5a, 6a) mainly developed according to corresponding trajectories intersecting at least one of said bending lines (4, 5, 6), so as to laterally delimiting a corresponding strip (10, 11, 12) of material which remains connected to said shaped laminar body (3; 3') at the level of two opposite edges (10a, 11 a, 12a); - lifting said strip (10, 11, 12) towards the inside of the concave area (7, 8, 9) defined by the corresponding bending line (4, 5, 6), so that said strip (10, 11, 12) and the areas of said shaped laminar body (3; 3') adjacent to said cuts (4a, 5a, 6a) delimit a guide channel (13, 14, 15) developed parallel to said bending line (4, 5, 6), suitable for slidingly housing one of said tubular elements; the perimeter profile of said shaped laminar body (3; 3') defining a recess provided with an open side at the level of one of said portions, extending at least as far as said intersection point to divide said portion into two edge portions (21, 22) separated and opposing each other with respect to a first one of said bending lines, one of said two edge portions (21, 22) having a shaped edge (21 a, 22a) adjacent to said recess and configured so as to be arranged against the corresponding shaped edge (21 a, 22a) of the other edge portion (21, 22) after said bending operations, characterized in that the shaped edge (21 a, 22a) of one of said edge portions (21, 22) comprises a projection suited to be fitted in a corresponding recess belonging to the shaped edge (21 a, 22a) of the other edge portion (21, 22) during the bending of said edge portions (21, 22), said method comprising the operation of fitting said projection into said recess. - providing a shaped laminar body (3; 3') in a material suitable for being plastically deformed; - bending said shaped laminar body (3; 3') along three bending lines (4, 5, 6) converging in an intersection point to delimit three corresponding portions (17, 18, 19) of said shaped laminar body (3; 3'), so as to define corresponding concave areas (7, 8, 9) suitable for housing said tubular elements; - making in said shaped laminar body (3; 3') two cuts (4a, 5a, 6a) mainly developed according to corresponding trajectories intersecting at least one of said bending lines (4, 5, 6), so as to laterally delimiting a corresponding strip (10, 11, 12) of material which remains connected to said shaped laminar body (3; 3') at the level of two opposite edges (10a, 11 a, 12a); - lifting said strip (10, 11, 12) towards the inside of the concave area (7, 8, 9) defined by the corresponding bending line (4, 5, 6), so that said strip (10, 11, 12) and the areas of said shaped laminar body (3; 3') adjacent to said cuts (4a, 5a, 6a) delimit a guide channel (13, 14, 15) developed parallel to said bending line (4, 5, 6), suitable for slidingly housing one of said tubular elements;