The uArm is a pretty awesome robot arm built around Arduino Mega 2560 that can take on a lot of tasks. It supports Python, Arduino, ROS, and other programming methods. It has a repeatability of 0.2mm and max payload of 500g. Ufactory has shared a guide that shows you how to combine your uArm with a slider.
You are going to need an ultrasonic sensor, color sensor, a control board, 1 x drag chain, and other simple components to pull this off. By putting your robot arm on a slider, you can easily pick and place items based on their color and other characteristics.