How is a case of a kettle made?

Electric tea kettles are made predominately of steel, iron, silver, aluminum, or a combination of plastic and metal. High-grade steel is typically used for the housing of all-metal kettles. Heat resistant plastics, such as low density polyethylene (LDPE), polypropylene (PP), or polystyrene (PS), comprise the upper housings of the kettles in some models with metal enclosures on the bases that contain the heating elements.

Add. A Kettle in Glaciology/Geology is a depression in the moraine or end landform left by the melting of an embedded block of ice. Waldon's Pond is a famous one.