Apparatus and methods are described including manufacturing a housing for an impeller of a blood pump by placing an inner lining around a mandrel, placing a cylindrical portion of a frame around the inner lining, and placing a distal portion of an elongate tube around a portion of the frame. While the distal portion of the elongate tube is disposed around the portion of the frame, the inner lining, the frame, and the distal portion of the elongate tube are heated, via the mandrel, and pressure is applied from outside the distal portion of the elongate tube, such as to cause the distal portion of the elongate tube to conform with a structure of the struts of the frame, and to cause the inner lining and the distal portion of the elongate tube to become coupled to the frame. Other applications are also described.