I wanted to do a water marble of gold and turquoise for my friend's wedding (it ended up looking totally ridiculous for wedding purposes so the day of I switched to $OPI's I'm Wired--terrible formula, fyi).
Still I thought the result was kind of cool. I used a metallic gold polish from a random brand I've found in the NYC area. It behaved in unexpected ways, I think maybe because of the metallic's increased drying speed?