Posted by abelsromero on Aug 17, 2017; 10:20pm
URL: https://discuss.asciidoctor.org/Asciidoctor-pdf-Custom-admonition-icons-tp5850p5852.html

If you mean use alternative icons, you can use some of the included ones: https://github.com/asciidoctor/asciidoctor-pdf/blob/master/docs/theming-guide.adoc#key-prefix-admonition-icon
Make sure you check the third footnote, contains a link to the available icons, check the correspondent .yml for the proper names. In my experience, not all work however, if there's some problem, it will appear in the output.

Otoh, if what you want is add a custom font with custom icons, I don't think it can't be done without messing with the code. You can try replicating the folder/file structure in prawn, but even if this works, I would not recommend it for maintenance sake.