Arduino Controlled Color sorting robotic arm 

This video demonstrates a color sorting robotic arm that works on arduino.
A push button operates the whole system, rack and pinon mechanism starts working where the cubes will drop from the feeder into the belt system, an IR sensor will sense the cube and pause momentarily allowing the color sensor to fetch the color from the cube then the belt starts working again. Once it reaches the second IR sensor the belt stops and the robotic arm operates and will take it into its desired location.
Some mistakes may arise and as you saw in the video, the arm malfunctioned in the blue box and that was because of the low power it was receiving. As a suggestion, use variable power supply.
Components are:
Robotic arm
Arduino
Conveyor belt
3D printed rack and pinion mechanism
3D printed cubes
Stepper motor to control the conveyor belt
12 Volt battery
2 IR sensors
1 color sensor