In this tutorial we will build a physical RGB (red, green, blue) LED (light emitting diode) colour mixer using Bare Conductive Paint. Each RGB LED has three internal light emitting diodes (LEDs) for each of the colours - red, green and blue. Further there is a lead to connect and control each of these internal diodes. Thus you can mix these three and get a whole range of new colours. The diagram below shows what one would commonly find inside a RGB LED.