Sorting beads the easy way
If you want to measure the blueness of an object, you can shine a pure blue light at it and then measure the reflected light intensity with a photodiode. Do the same for red and green light, and you can get an RGB color value. Conversely, you can shine a white light at an object and use three photodiodes with the appropriate color filters to calculate your RGB levels. This sorter, built by Redditor Dumjim, relies on these principles to organize large quantities of beads.
This machine sorts the kinds of beads used for beadwork crafting. Those may come in individual containers, but they soon end up mixed up. But now, Dumjim can quickly and easily sort those beads by color. It utilizes a 3D-printed frame and mechanisms, which Dumjim designed in Autodesk Inventor CAD software.
The brain of the machine is an Arduino Uno, which inspects each bead using a color sensor that operates with white light with filtered photodiodes. A unique servo-driven mechanism feeds beads from a hopper down to the sensor. Based on the color values, it uses a second servo-driven mechanism to drop the beads down a chute and into separate containers. These same principles would work for sorting uniform objects of any kind by color, but it is especially suited to the tiny beads that frustrate crafters.
You can see it in action here!