colour sensor robotic arm

please help me to how to make colour sensor robotic arm

You probably need to put a camera on the arm, but a Pi would be better than an Arduino to read the output.

Here is a color sensor for Arduino. The page has links to example code and hookup guide.

How to make a robot arm is a very complex subject. We can't be of much help until we know a lot more detail about what you want.

groundFungus: Here is a color sensor for Arduino. The page has links to example code and hookup guide.

How to make a robot arm is a very complex subject. We can't be of much help until we know a lot more detail about what you want.

That is neat I did not know that existed.

You can build a surprisingly good color sensor with just a LDR (Light Dependent Resistor) and RGB LED. Many (most?) LDR sensors are more sensitive to green (like the human eye). Turn on each color and measure the reflected light with the LDR.