A block characterized in that it comprises: a- two side panels (1, 2) of rectangular shape and of equal dimensions, facing each other and parallel to each other, b- an outer partition located at 90° of said two side panels, said outer partition having a length equal to the height of the side panels, said outer partition having a width smaller than the distance between the side panels, said outer partition being attached to each of the side panels at its longitudinal ends by means of a first and a second tab (34, 35), each of said tabs being perpendicular to the outer partition and attached to the inside surface of the edge that constitutes the height of the outer partition, said outer partition being attached to the side panels so that one of its edges extends beyond one of the edges of the side panel, said outer partition having at least one through hole (30, 31, 32, 33), c- a third tab and a fourth tab projecting from the edges of the outer partition and beyond the edges of the side panels, perpendicular to said outer partition and without reaching the edges of each side panel that are farther from the outer partition, said third and fourth tabs being attached to the inside edges of the side panels, d- one or more inner partitions (4, 5, 6, 7) attached to the inside surfaces of the two side panels and of the third and fourth tabs, each of said inner partitions extending parallel to the outer partition, from the same end as the outer partition and having the same length as said outer partition, each of the inner partitions having at least one through hole, the inner partition that is farthest from the outer partition being attached to the ends of the third and fourth tabs that are farther from the outer partition. a- two side panels (1, 2) of rectangular shape and of equal dimensions, facing each other and parallel to each other, b- an outer partition located at 90° of said two side panels, said outer partition having a length equal to the height of the side panels, said outer partition having a width smaller than the distance between the side panels, said outer partition being attached to each of the side panels at its longitudinal ends by means of a first and a second tab (34, 35), each of said tabs being perpendicular to the outer partition and attached to the inside surface of the edge that constitutes the height of the outer partition, said outer partition being attached to the side panels so that one of its edges extends beyond one of the edges of the side panel, said outer partition having at least one through hole (30, 31, 32, 33), c- a third tab and a fourth tab projecting from the edges of the outer partition and beyond the edges of the side panels, perpendicular to said outer partition and without reaching the edges of each side panel that are farther from the outer partition, said third and fourth tabs being attached to the inside edges of the side panels, d- one or more inner partitions (4, 5, 6, 7) attached to the inside surfaces of the two side panels and of the third and fourth tabs, each of said inner partitions extending parallel to the outer partition, from the same end as the outer partition and having the same length as said outer partition, each of the inner partitions having at least one through hole, the inner partition that is farthest from the outer partition being attached to the ends of the third and fourth tabs that are farther from the outer partition.