I am NOT asking about etching OR engraving, the process I need to
learn will result in letters raised in relief from the surface of
John, etching is indeed a good way to do this. But you are not
etching the letters. You etch away the background. That gives you the
raised letters. Using a photo resist, you can get great precision in
the letters. Less precision in the background, as that's the bottom
of the etched surface.
One process that may work quite well for you is if you can find a
graphic arts company that still does linotype or zinc/magnesium plate
etching, as used to be common for printing plates. This is still used
now and then by small printers doing art printing rather than high
volume, where the specifics of ink from a raised plate are desired.
Anyway, those firms can take your image on paper, and etch it onto
those plates. Good ones can control the angle of the side walls of
the etch to be steeper and deeper than normally used for printing,
though you don't generally get vertical walls. Still, this often is
quite enough for uses like yours. Occasionally, this process can also
be used to produce rubber stamps, another possible place to look for
having this done. Those zinc or magnesium (the latter seems more
common these days)plates are then used to make a master, from which
rubber molds are made, for lost wax casting. If you've found a rubber
stamp company, they can make your text as a rubber stamp that reads
correctly on the rubber, instead of the usual reverse, and they
don't have to mount the rubber onto the stamp handle, leaving you
with a flexible piece of sheet rubber with the letters raised as you
desire. Again, this can eventually be used to generate a mold, or the
rubber sheet can be directly burned out and cast.
Other ways to do this would be engraving, via a pantograph or
computer controlled engraving machine (using actual rotating cutters,
not a diamond drag engraving cutter), cutting your lettering in a
reversed image into whatever sort of plate or material desired, and
you then can press wax or other impression material into this plate.
When removed, your wax now has the correct reading lettering raised
above it's background. A hint, if you do this. Use somewhat soft
sheet wax (warm ordinary wax sheet until pliable), and place a sheet
of ordinary plastic kitchen wrap (saran wrap or similar) between the
wax and the engraved master as a relief agent so you can remove the
wax without damage. If the plastic wrap is sprayed first with a mold
release agent, it can be easily peeled from the wax, leaving you with
the image on the wax.
Hope that helps