Composite tooling systems and methods of manufacturing composite stringers of aircraft are provided herein. A composite tooling system includes a layup tool and an articulating stringer mandrel. The layup tool has a contoured surface with portions having different surface complexities. The articulating stringer mandrel includes two rigid mandrel elements and a cable. The first rigid mandrel element defines a first aperture, a first stringer surface, and a first bottom surface. The second rigid mandrel element is adjacent to the first rigid mandrel element and defines a second aperture, a second stringer surface, and a second bottom surface. A first length of the first rigid mandrel element cooperates with the surface complexity and a second length of the second rigid mandrel element cooperates with the surface complexity at the second rigid mandrel element so that a gap between the rigid mandrel elements does not exceed a predetermined gap threshold.