A method is described by which blades of aerofoil section can be manufactured on a laboratory scale. Emphasis has been placed upon cheapness, rapid production, and the ability to obtain an accurate representation of the blade profile for a large aspect ratio of 3·5. In addition, for a series of experiments with a cascade in water, the blades were to be made from a material which did not require the use of a protective paint on the surfaces. To satisfy the above requirements a casting process was adopted, and the blades were made from a plastic resin material. Although the discussion presented is confined to the production of blades, the method can easily be extended to the manufacture of impeller hubs, fairings, nozzles, and so on.