A manipulation tool is disclosed for producing cell material having multiple biological cells, which have a predefined geometrical arrangement. The tool includes a tool body, whose surface at least partially contacts the cell material, and a setting device for adjusting the tool body by a continuous expansion, so that geometrical properties of the surface change and an interior of the tool body is enlarged. The setting device is adapted to expand the tool body at an advance velocity in a range from 0.1 μm/h to 1 mm/h.
