Modular tooling for manufacturing multispar torsion boxes with different web heights, the modular tooling comprising: - a mandrel module having a hollow beam geometry which comprises a first base (11.1) and a second base (11.2) opposite to the first base (11.1), and two walls (11.3, 11.4) extending between said first base (11.1) and said second base (11.2), and - at least one spacer module (12A, 12B, 12C, 12D) configured for coupling with the mandrel module, wherein the web height of a multispar torsion box is defined by the coupling between the mandrel module and the at least one spacer module (12A, 12B, 12C, 12D), characterized in that: the at least one spacer module comprises a hollow beam geometry which comprises a first base (12A.1) and a second base (12A.2) opposite to the first base (12A.1), and two walls (12A.3, 12A.4) extending between said first base (12A.1) and said second base (12A.2), and in that the mandrel module and the spacer module are configured to stack with each other, such that a base of one of the mandrel module and the spacer module is supported on a base of the other of the mandrel module and the spacer module, the stacking thus having a hollow beam geometry, said hollow beam geometry of the stacking comprising: - two opposed bases (15.1, 15.2), one corresponding to a base (11.1, 11.2) of the mandrel module, and the other corresponding to a base (12A.1, 12A.2) of the spacer module, and two external walls defined by the walls (11.3, 11.4) of the mandrel module and the walls (12A.3, 12A.4) of the spacer module. - a mandrel module having a hollow beam geometry which comprises a first base (11.1) and a second base (11.2) opposite to the first base (11.1), and two walls (11.3, 11.4) extending between said first base (11.1) and said second base (11.2), and - at least one spacer module (12A, 12B, 12C, 12D) configured for coupling with the mandrel module, wherein the web height of a multispar torsion box is defined by the coupling between the mandrel module and the at least one spacer module (12A, 12B, 12C, 12D), characterized in that: the at least one spacer module comprises a hollow beam geometry which comprises a first base (12A.1) and a second base (12A.2) opposite to the first base (12A.1), and two walls (12A.3, 12A.4) extending between said first base (12A.1) and said second base (12A.2), and in that the mandrel module and the spacer module are configured to stack with each other, such that a base of one of the mandrel module and the spacer module is supported on a base of the other of the mandrel module and the spacer module, the stacking thus having a hollow beam geometry, said hollow beam geometry of the stacking comprising: - two opposed bases (15.1, 15.2), one corresponding to a base (11.1, 11.2) of the mandrel module, and the other corresponding to a base (12A.1, 12A.2) of the spacer module, and two external walls defined by the walls (11.3, 11.4) of the mandrel module and the walls (12A.3, 12A.4) of the spacer module. the at least one spacer module comprises a hollow beam geometry which comprises a first base (12A.1) and a second base (12A.2) opposite to the first base (12A.1), and two walls (12A.3, 12A.4) extending between said first base (12A.1) and said second base (12A.2), and in that the mandrel module and the spacer module are configured to stack with each other, such that a base of one of the mandrel module and the spacer module is supported on a base of the other of the mandrel module and the spacer module, the stacking thus having a hollow beam geometry, said hollow beam geometry of the stacking comprising: - two opposed bases (15.1, 15.2), one corresponding to a base (11.1, 11.2) of the mandrel module, and the other corresponding to a base (12A.1, 12A.2) of the spacer module, and - two opposed bases (15.1, 15.2), one corresponding to a base (11.1, 11.2) of the mandrel module, and the other corresponding to a base (12A.1, 12A.2) of the spacer module, and two external walls defined by the walls (11.3, 11.4) of the mandrel module and the walls (12A.3, 12A.4) of the spacer module.