Method for making a composite element comprising the steps of: a) providing a core comprising a plurality of faces adjacent to each other and connected to each other through edges , b) providing a panel in one piece dimensioned to cover at least a surface region of said core which comprises at least a portion of at least two faces adjacent and connected to each other through at least one of said edges , said panel having a thickness (d), an inner surface adapted to be operatively joined to said core and an outer surface opposite to said inner surface , c) coupling said panel to said core so as one of said at least two faces joins at least partially to a portion of said inner surface of said panel , d) forming on said panel at least a folding channel defining and connecting to each other at least two portions adjacent of said panel through a reduced portion (d1, d2) of said thickness (d), said at least a folding channel being formed, moreover, operatively corresponding to said at least one of said edges of said core , e) folding said panel along said folding channel so as to join the portion of inner surface of each of said at least two portions to the corresponding one of said at least two faces adjacent of said core , characterized in that in said step d) said at least a folding channel is formed on said inner surface by means of a cutting tool , wherein said cutting tool is provided with a cutting edge comprising a first cutting edge portion and a second cutting edge portion consecutive each other so as to define a cutting edge vertex , said first cutting edge portion and said second portion of cutting edge further defining an internal angle (A1) comprised between 110 and 70 degrees, and a bisector (B1) of said internal angle (A1) operatively defining an engagement angle (A2) comprised between 3 and 20 degrees with the other of said at least two faces which is adjacent to that face at least partially joined to the inner surface of said panel . a) providing a core comprising a plurality of faces adjacent to each other and connected to each other through edges , b) providing a panel in one piece dimensioned to cover at least a surface region of said core which comprises at least a portion of at least two faces adjacent and connected to each other through at least one of said edges , said panel having a thickness (d), an inner surface adapted to be operatively joined to said core and an outer surface opposite to said inner surface , c) coupling said panel to said core so as one of said at least two faces joins at least partially to a portion of said inner surface of said panel , d) forming on said panel at least a folding channel defining and connecting to each other at least two portions adjacent of said panel through a reduced portion (d1, d2) of said thickness (d), said at least a folding channel being formed, moreover, operatively corresponding to said at least one of said edges of said core , e) folding said panel along said folding channel so as to join the portion of inner surface of each of said at least two portions to the corresponding one of said at least two faces adjacent of said core , in said step d) said at least a folding channel is formed on said inner surface by means of a cutting tool , wherein said cutting tool is provided with a cutting edge comprising a first cutting edge portion and a second cutting edge portion consecutive each other so as to define a cutting edge vertex , said first cutting edge portion and said second portion of cutting edge further defining an internal angle (A1) comprised between 110 and 70 degrees, and a bisector (B1) of said internal angle (A1) operatively defining an engagement angle (A2) comprised between 3 and 20 degrees with the other of said at least two faces which is adjacent to that face at least partially joined to the inner surface of said panel . <EOS>