@aliendre it's a little more complicated to make an electrode. It is necessary to know the method of erosion, either in a straight dive or in orbit, the material "copper or graphite" if the shape is concave, convex or both. If it is a rough electrode, finishing because all its information which is crucial gives you a GAP "spark length " once this value is known it is either subtracted or added to your electrode.
why don't you put the gap on the milling machine or the wire machine, so you only draw an electrode and the tech workshop but the gap that needs directly in these tool parameters