[HELP] Suggestions for writing on harmonica metal plates

[Sunset Machine]

Along those lines, maybe a photocopy of a signature can be put to tee-shirt iron-on plastic, and use a photo-resist method of etching. 

Alternatively, paint the metal black, use a scribe to scratch a signature with, and then reverse electro plate to etch. Here's a guy making reed valves that way:
https://www.youtube.com/watch?v=jEnNMTMZadw