Copper or graphite can also be used as the electrode. Things made of copper are lighter and smaller, but they are expensive, and it is also troublesome to add a molding to CNC milling. The particles made of graphite are large and suitable for primary processing, but graphite is cheaper, lighter than copper and easy to process. At present, most of the EDM shops outside are carbon workers and EDM. If you pull out the mold and copy a shape for them, they will directly process the graphite and send it back to you, so you don't have to go to a carbon worker to make graphite and then go to EDM.