A method for producing a waveguide device, including producing a core of a non-conductive material. The core has side walls with outer surfaces and inner surfaces, the inner surfaces defining a waveguide channel. A layer of conductive metal is deposited on the inner surfaces by immersion in a fluid of reactants. The core includes at least one hole between the outer and inner surfaces, specifically used to encourage the removal of bubbles from the channel and/or the circulation of the fluid during the immersion.