Mild steel for wood, meat might need stainless for health and safety if not then mild steel would be ok. It doesn't need to be very hot if you want a sharp image.
Thanks for the links lads, been looking on and off for electro etching for years.
Only problem is none of those linked would work on a convex surface unless a style like a soldering iron up to 8mm square head.
Cant send out to be done due to punters wanting stuff as soon as its made. I have some large orders coming up for SA and Thailand, could really make use of something.