I did not like any of the nail embossing techniques I saw builders use on their models. The were just too out of scale as indicated by AllanPK69. I decided for my build that I would not try to duplicate the nail patterns, because at scale, nobody would see them unless they put their face on top on the model. However, I did not want the copper surface to be shiny smooth either as that would be unrealistic as well. So, I made a radical choice and just simulated the appearance of nails by embossing the copper plate with sandpaper. This gave a high density of dimples (pseudo nails) but no pattern for the body of the plate. I used my fine tooth miter saw blade teeth to emboss the plate edges for fine line of nails. It was easy to do, though tedious as any other method and it got the more realistic effect I wanted. You can see how I did it and the results starting at post #634 on the link below.
Jon
Jon