Abstract: The present invention relates to a hybrid lay-up tool comprising a thin metallic working surface and a composite back structure. The working surface may be an Invar working surface, and the working surface and the back structure may be coupled using a self-locking connection mechanism. The present invention also relates to a method for providing a hybrid lay-up tool. The method may include providing a metallic face sheet, providing a composite back structure, and operably coupling the metallic face sheet with the composite back structure using a self-locking connection mechanism.