A method and tool for mass manufacturing convertible roofs having an outer shell, a frame and lateral linkage parts for supporting the outer shell, the outer shell including at least two outer shell parts is provided. The method includes the steps of providing an upper tool fixture and a lower tool fixture, aligning and assembling the frame and outer shell in the lower tool fixture such that the frame and outer shell are upside down, aligning and assembling connection members onto the frame part so the roof can fittingly engage the windshield frame when the roof is in a closed position, and lowering the lateral linkage parts onto the assembled frame and outer shell using the upper tool fixture.