Koftgari, How is it done?

[Jeff Pringle]

There are a few ways to execute the technique, some traditions use a steel needle or scriber to crosshatch the ground. You can also erase extra crosshatching by burnishing, in the link it looks like they are using a punch to do most of the smoothing out.
There is not a whole lot of info on the technique out there, compared to other traditional crafts.