I had the luck to watch as Erik Boessler(sp?)did one for me.He did it all "freehand", no pattern, and the whole thing only took a few minutes.He first cut the borders,"shaded" it with a shadeing(sp)tool and then cut the lines(crosshatching and all) with a graver.He used a swivel vise about chest high,turning it rather than the graver,most of the time.He seemed to sharpen the tool automatically,w/o thinking. Note the borders around the holes in the plate,these are necessary to prevent disturbing the fit of the clawmounts.Neither the bases or "claws" were hardened.Others I watched,did it essentially the same way.
Mike