I've done a Mark 2. 8mm round brass bar.
Right of the pencil line is the initial shape, a few little tweaks and the images to the left are the result
Tried it on leather. Sorry about the state of the axe. A week in the hands of my Scouts and I haven't gotten round to cleaning it up.
And a close up of the image in wood. It has worked out at 7mm by 5mm
It's been a while since I resorted to using a magnifying glass.