In this paper, we present PortaChrome, a portable light source that can be attached to everyday objects to reprogram the color and texture of surfaces that come in contact with them. When PortaChrome makes contact with objects previously coated with photochromic dye, the UV and RGB LEDs inside PortaChrome create multi-color textures on the objects. In contrast to prior work, which used projectors for the color-change, PortaChrome has a thin and flexible form factor, which allows the color-change process to be integrated into everyday user interaction. Because of the close distance between the light source and the photochromic object, PortaChrome creates color textures in less than 4 minutes on average, which is 8 times faster than prior work. We demonstrate PortaChrome with four application examples, including data visualizations on textiles and dynamic designs on wearables.