If you use a bare plate then you would have to apply some sort of rust prevention unless you use stainless. Not sure if the etching would be as visible on stainless. You could apply some oil but that would have to be reapplied but if you were to apply a varnish it would last longer. The same as applying varnish on polished copper to keep the shine. You could make your own plate out of any metal you have but just be aware rust could be a problem. Etched bare plate is normally black so there is the contrast between the lighter coloured material and black etching. The chrome is good if it has copper underneath the chrome as you get the contrast of the 2 different material colours.

As for etching then having the chrome plate applied would probably be a waste. Normally they put a copper/nickel coating to help the chrome adhere to the base material. Chrome is not very smooth when applied and it is normally polished and as the etching isn't very deep when the chrome is polished it probably would not be visible and may even disappear with the base copper/nickel.

I did have access to an engraver at one stage and used to engrave the neck plates and fill with a special paint that was almost as hard as ceramic when dried. It was made for outside as well as inside and was used for making signage. Only problem was it was over $60 for 250ml but work was paying so all was good but it did go along way.

You could use a fine engraving chisel and hand engrave the chromed plate and fill with some sort of paint or coloured varnish.