In the basic electroforming process, an electrolytic bath is used to deposit nickel or other electroformable metal onto a conductive surface of a model (mandrel). Once the deposited  material has been built up to the desired thickness, the electroform is parted from the substrate.  This process allows precise replication of the mandrel surface texture and geometry at low unit cost with high repeatability and excellent process control.
If the mandrel is made of a non-conductive material it can be coated with a thin conductive layer.