cast clear casting resin into a silicon mold?
Here's They usually have that (or something very similar) in craft type stores that carry fake flowers (e.g., Michael's, AC Moore, Hobby Lobby). Good luck with your project, ~Dr. B.~
The basic color wheel that is commonly referred to in visual arts consists of primary, secondary, and tertiary colors. The wheel is not meant to represent all colors, but specifically gradations between different fundamental shades. Anyone can create a color specific to particular subset of colors however, and on such a color wheel, perhaps a metallic shades color wheel, you might find gold, silver, and copper. But other than that, no.