Photo series of etching by Montejano

[Montejano]

Hello friends:

I will continue to show some of my work, in other forums and have seen this work.

It is an engraving after a design by Thor and some gold inlay and copper wire. I show a few pictures of the process of drawing in pencil (previous sketch). After I modified the sketch and suppressed characters.
Eventually it became a design of Thor and some additional decorations.

Montejano

-----------------

 

[Montejano]

Antonio Montejano

 

[KaiLawson]

Can anyone tell me how the initial etching was accomplished? Was it a resist/acid etch, or something more complicated? I'm looking to etch and undercut some heat treated steel for wire inlay, which looks to be exactly what was done here. Any advice, tips or tutorials?