We propose a novel ball-type input/output (I/O) device—the ChameleonBall—that allows users to interact with colors in the real world. The ChameleonBall mainly consists of multiple color I/O units in an acrylic ball. It can detect the colors of objects in the real world and emit similar colors. We have developed a prototype system and a few applications using this device. Keywords I/O device, color sensor, LED, ball ACM Classification Keywords H5.2 [Information interfaces and presentation]: User Interfaces. General Terms Human Factor