I have just the thing you’re looking for, an electrolytic etching
tutorial I just finished writing a few weeks ago:
If you have any questions, feel free to ask. The chemicals are
pretty safe and if you really really don’t want to use chemicals I’ve
heard you can use salt.
One note is that I have had random luck with silver (I’ve only done
it twice). On a small ring it came out perfect, but on a bigger
pendant it left a sort of holey texture in the etched away parts.
Good luck! m