Jinsun Park is a South Korean designer that invented this tool. He was probably inspired by the eyedropper tool from Photoshop which allows you to pick the color of any object on the canvas and use it for drawing other objects on your PC. The Park’s invention does the same thing, but in the real world. At the end of this concept tool is a color sensor that scans a real world color. After the scanning process a micro-computer calculates the amounts of red, green and blue inks that are needed to recreate the scanned color.
On the other end is a ball point where the mixed ink flows from. It is a bit strange that the pen uses the RGB (Red-Green-Blue) color model which is typical for digital displays as PC monitors and TV. Normally for printings computers use the CMYK model (Cyan-Magenta-Yellow-blacK). But aside of this, the ability to paint with color of the apple or the strawberry you just saw is quite interesting.
Well, I’m not sure what is the practical value of this pen. But I’m not an artist, however, may be some painter or graphic designer will be able to give competent opinion.