Question: In the current draft of my book, the evil dictator whose body is encased in a silver alloy talks basically by allowing magic to move to seep into the silver shell, dispelling it and causing vibrations.

This voice sounds alien, imperial, and metallic. In order to represent this, I'm currently using a different font. (Specifically Kino MT.)

I do something similar with a group that constantly wear helmets that filter out certain wavelengths of sound, and use the 'Cracked' font.

They also sometimes speak in an imperial dialect which I represent with angle brackets.

Is this just going to reek of tacky amateurishness and such?

Answer: 
**Think about it: Are you reading this answer on paper, or on a (color) screen? The convention may change quickly, if readers accept changes** 

Conventional wisdom says not to play 'games' with typography (until/unless one is a big-name author), but that convention is based back in the history/technology/economics of movable type and printing presses. However, if we write and read primarily on screens, (thus freed from the constraints of paper and printing processes), we can do it differently -- if (and *only* if) the changes tell the story to the intended audience sufficiently better. So much so that the readers' approval is evident to the current gatekeepers.

That said, conventions change with the technology and reader expectations/enjoyment. If using different fonts, italics, bold or punctuation unconventionally tells stories more effectively, I think that will *eventually* win out. At present, the expectations of agents, editors and publishers are the gatekeepers, but those gates aren't locked -- and effective storytelling is the key.

Two examples of interest: In *Startide Rising*, author David Brin used a variety of typographic signs (uppercase, paired punctuation marks such as '::') to indicate alien/telepathic 'speech.' It was his second novel published, and won the Hugo award.

In *The Stars My Destination*, Alfred Bester uses some interesting language-on-paper techniques to convey synesthesia (a scrambling between senses.) Most serious fans consider it one of his best books.

Your mileage may vary; I'm hoping the conventions evolve.
As noted above, "generally inadvisable" is on the mark.

However, if you consider your book to be more along the lines of entertainment, than along the lines of literature, you might do it. Really, the choice is yours.

Think of it this way: If you show up for a job interview, you dress in accordance with expectations. Same with books.

I write this not as a reviewer or publsher, but as someone who has browsed many books on the library shelves, always fiction, not necessarily in a genre that appeals to me. Although books with prominent decorative elements (including styled text) are uncommon, they are occasionally seen among recently-issued popular books, probably because those books are intended to appeal to the "soon to be a movie or TV show" market.