Summary

A small 5 cm hollow sphere which has a base and a hole for a 5mm LED.

I used mine with an RGB led and Arduino, and made it into a Pomodoro timer. It starts green, fades to red over 25 minutes, then for 4 minutes glows blue, signalling a stretch break.

Detailed instructions for creating the Pomodoro timer are below.

Instructions

Print out the Sphere in a neutral or white colour. Insert 5mm LED of your choice into the bottom and power it however you like!

If you want to build the Pomodoro timer which I did, follow this instructable for building the RGB LED circuit for the Arduino, which is what I used: http://www.instructables.com/id/Fading-RGB-LED-Arduino/. It give clear steps and materials required.

The code I wrote for the Pomodoro specific logic is here:

#define RED 9  #define GREEN 10  #define BLUE 11  void setup() {    pinMode(GREEN, OUTPUT);    pinMode(BLUE, OUTPUT);    pinMode(RED, OUTPUT);    digitalWrite(GREEN, HIGH);    digitalWrite(BLUE, LOW);    digitalWrite(RED, LOW);  }  int redVal;  int blueVal;  int greenVal;  int val;  void loop() {    // 25 minute green to red     int redVal = 0;    int blueVal = 0;    int greenVal = 255;    for( int i = 0 ; i < 255 ; i += 1 ){      greenVal -= 1;      redVal += 1;      analogWrite( GREEN, greenVal );      analogWrite( RED, redVal );      delay( 5882 );    }    // blink red     for ( int i = 0; i < 60; i++ ) {      redVal = ( redVal == 0 ) ? 255 : 0;      analogWrite( RED, redVal );      delay ( 500 );    }    // 4 minute solid blue    analogWrite( RED, 0 );    analogWrite( BLUE, 255 );    delay( 240000 );    // blink blue     for ( int i = 0; i < 60; i++ ) {      val = ( val == 0 ) ? 255 : 0;      analogWrite( BLUE, val );      delay ( 500 );    }    analogWrite ( BLUE, 0 );  }

LED Globe