Method of forming a component of complex shape from an Al-alloy sheet or a Mg-alloy sheet. The method includes the steps of: a) heating the sheet to a temperature below the solution heat treatment (SHT) temperature for the alloy; b) forming the heated sheet between heated dies into or towards the complex shape; c) heating the sheet to at least its SHT temperature and substantially maintaining that temperature until SHT has been completed; and d) quenching the solution heat treated sheet between cold dies and at the same time completing the forming into the complex shape or maintaining that shape.