Abstract: A 3D printer is described, which comprises a housing providing a printing chamber, a liquid print head, movably mounted within the housing, for dispensing a liquid, a print bed at the base of the printing chamber for receiving an object to be fully or partially filled by the liquid print head, and one or more apertures for drawing air from the object using a vacuum pump. In this way, the filling of an object with printed liquid can be achieved more effectively than relying on gravity alone, and a reduction in the number of air bubbles can be achieved.