The invention concerns machinery for molding and assembling of at least two part objects and of plastics, e.g. two ball shells, which can be assembled to a hollow ball, as molding and assembly can take place in the same tool and continuously in the same work procedure. This can be realized by the two turnable middle parts and of the tool, respectively are supplied with the mold cavities and, where the assembling of the part objects and can take place, when the respective tool cavities meet during the rotation, at the same time as the closing of the mold. During the closing there can simultaneously be molded new part objects and in the opposite placed mold cavities and in the two turnable mold part and. If it is necessary in respect of the material or the design of the part objects, there can after the molding of the part objects be applied e.g. heat on the respective boundary surfaces, which shall shape the assembling. This can suitably be fit into the steps, which the turnable middle parts and run through. The part objects and can possibly as well as be assembly by a snap- or click function, which is a pure mechanical assembling.