A system for forming a hollow body may include at least one closing unit positioned beneath the die of a tube extrusion device. The closing unit may include a first vertical closing plate and second vertical closing plate. Specifically, an upper horizontal closing plate is cantilevered to the first vertical closing plate carrying an upper mold half, while a lower horizontal supporting plate is cantilevered to the second vertical closing plate carrying a lower mold half. At least one hydraulic cylinder may connect to the horizontal supporting plate and be adapted to vertically displace the lower horizontal closing plate. The closing unit is configured in such a way that when the vertical closing plates are moved toward each other, the upper horizontal closing plate and the lower horizontal supporting plate interlock. The system can be configured to produce oblong hollow bodies requiring a horizontal mold parting plane.