your so Kind James.. your work is Briliant too..
this is my approch to Brass etching… others may differ..
First of all you need a Drawing program, I use Coral Draw, its reasonably easy to use, not as expensive as most CAD (computer aided drawing) software, and can save the Data into various Data formats.
then you need to find some one that can do etchings, and ask them at the same time what etchings process they use (Positive or Negative) and also very important what Data formats they except.
Q "what does Positive or Negative mean"
I hear the first question, there are two ways to etch and this depends on whether the metal has a positive or negative photo film on it.
if the film is positive you can do all your drawings in Black (remains) white gets etched away, of course negative is visa versa.
When doing your drawing, one of the simple rules to follow, no lines are meant to be thinner than the metal thickness your etching.
Now you can do your drawing, but thinking about that, when etching, both sides of the metal get etched at the same time, so you need a front and rear side, were the rear side is a mirrored version of the front side.
And if you would like things like nuts and bolts to stand out (relief) (2D / 3D effect) then careful thought needs to be taken as to which parts of the front side needs to be omitted, as the rear side is always the full picture.
So that would mean that the rear side is always flat and the front side now has indentations, if you would like the 3D effect that both sides of the object have indentations (relief) then you need to draw two fronts and two backs, or used the folding technique.
The following photos, show a boarder front and back, plus my version of turnbuckles were the top turnbuckle gets folded over the bottom turnbuckle, this giving a turnbuckle that is 0.4mm thick, but the bolt part is only 0.2mm thick.
also a Picture description of my pulley's/blocks