I am trying to make shapes for color mixing in additve mode and subtractive mode.
Additive mode is easy, as you have only to add color components of RGB color.
Subtractive mode is a bit complicated.
You need to convert RGB value to YMCK value, calculate mean Value of the components of YMCK value, and restore calculated YMCK value to RGB value.
Please enjoy color mixing, in the attatched Visio drawing.