I have noticed there are often questions on how to do electrodes on SW.  As a reasonably advanced user of surfacing etc I was suprised at how challenging this was to complete.  I now have a solution that works for me, and I can usually knock out a complex electrode in about 10 minutes.

This is my usual workflow;

1. Create electrode part (shape large enough to cover electrode area).
2. Assemble with cavity I want to create the electrode for.
3. Create cavity feature in the electrode part.

I then edit the electrode part using a combination of the following methods to obtain the spark gap required;

1. Delete face on the rear of the electrode to create a surface model.
2. Create an offset surface (select the surface in the surface bodies area, not each individual face) for the applicable spark gap.
3. Cap the rear of the surface (this can sometimes be a bit of a challenge to do well).  Creating a surface and doing a mutual trim is the best option often.
4. Make the electrode solid.
5. Extend the electrode to clear the top of the cavity and allow for machining.
6. Add a base for mounting.

The above method is pretty parametric, as it doesn't involve selecting exact faces etc, so edits to the cavity are reflected in the electrode.

We also tend to need a finisher and a rougher so I will create configurations with different surface offsets.  By cutting an F or R into the base, when programming the CNC unmachined material shows up a different colour, allowing the programmer to be careful with which elctrode is being done.  Configurations are great in SolidCam, as we don't need to program the whole electrode.

Attached is an example of this.

Hopefully this helps other people with this common problem.