What do you need

  1. Arduino board
  2. Resistors
  3. A red, green and blue led
  4. paper
  5. tissue paper
  6. colored straws
  7. piece of plastic scratched with sandpaper

Color mixing

Color mixing is the ability that our eyes have to combine different light colors and create a new color
AdditiveColorMixing.png
A additive (light) color mixing diagram

According to this diagram, if you turn on both red and blue light mixed together you should get a violet light.

Program your chip so that you create the following colored light: Violet (red & blue), Turquoise (blue & green) and yellow (green & red)

Modify the sketch so that the emitted light goes in order: red, yellow, green, turquioise, blue violet and back to red. It should pause about half a second between each color change.

Hint: One way to make the color mixing work better is to diffuse the light, in a light box. You can make a light box out of plain paper, scissors and some tape. Just make a paper box and cut a hole in it. Fill the box with tissue paper. The tissue acts as a diffuser, helping the light mix nicely

diffusercut.jpg tissuediffuse_t.jpg


Alternatively, place a straw over your led. Use random to create a flickering light:
int led=9;
int val=0;
int delayVal=0;

void setup(){
randomSeed(0);
pinMode(led,OUTPUT);
}

void loop(){
    val=random(100,255);
    analogWrite(led,val);
    delayVal=random(50,150);
    delay(delayVal);
}
}
Source:http://www.ladyada.net/learn/arduino/lesson3.html