u/Gud_Boi-

Saw some other fella do something like this. I filled the engravings with nail polish, using a single coat of white under the colors to help them pop. Cleaned the site with non-acetone polish remover and used simple scotch tape to prevent colors bleeding over each other while doing multiple coats. I used an old plastic membership card to swipe the bulk off immediately after applying and the polish remover on a cloth to gently wipe the rest. Light coat of oil and it's done.

I know, it's corny, but I like it.