Ahoy,
I found a way with Google, but I don't know how fun this will be. Like Mica has said, it is basically the applique (accent aigu) of thin gold foil onto a prepared, raised surface that has a gold embedded adhesive on it (a "raised guilding" technique, I think they called it). Maybe put a thin layer of the adhesive on a flat metal surface, cover the letters with aqueous primer, repeat, and then apply the gold foil really carefully?
But, what the heck do I know, though? I can't even frost a cake.
Good luck, and I hope if nothin' else, these links might give you a place to look next for a workable answer-
Raised letters:
https://www.calligraphy-skills.com/gold-leaf-technique.html Gold leaf and gold leaf paint techniques:
http://homeguides.sfgate.com/apply-gold-leaf-embossed-surfaces-89758.htmlCheers,
-Zut