A housing cage (1) comprising walls (2) defining sides of the housing cage and having wall sections (3). A plurality of contact surfaces (4), each of which is connected to one of said wall sections, are arranged so as to support built-in modules which are held in the housing cage (1). Each of the wall sections (3) is connected only on one first side (5) to its associated wall (2) of the housing cage (1), and the other sides of the wall sections (3) are spaced from the associated wall (2) of the housing cage (1) by incisions (6) in said associated wall, so that each of the wall sections (3) can be bent along the first side (5) with respect to its associated wall (2) of the housing cage (1).