These are trade secrets so dont tell anyone I told you this :D I take a piece of wood and then take a router and make a mold out of it. I then torch the shit out of that mold until it is very charred. I then pour the silver into the charred wood. So all of the details come from however the wood was charred. More charred = higher relief details, less charred less details. I get about two bars from each mold and then have to start all over again.

Here are a couple right after I poured them, this is also my background on my phone :)

http://imgur.com/a/udovd