Now on to the science project that is the Frankenpolish. Custom blending nail polish is not a new technique. For decades, manicurists have been making their own mixes for everything from fashion shows to editorial shoots, creating colors on the fly. Now you can replicate the process at home. All you need is an empty polish bottle and your creativity. The easiest way to start is by adding pure black or pure white to colors that are too light or dark. With dove gray being such a big trend in nails, I loved the the custom shade CND created for Costello Tagliapietra's Fall 2008 collection. It's a mix of CND Retro White, Black Platinum, Voodoo and Hot Pop Blue.