Today's environments are populated with a growing number of electric devices which come in diverse form factors and provide a plethora of functions. However, rich interaction with these devices can become challenging if they need be controlled from a distance, or are too small to accommodate user interfaces on their own. In this work, we explore PICOntrol, a new approach using an off-the-shelf handheld pico projector for direct control of physical devices through visible light. The projected image serves a dual purpose by simultaneously presenting a visible interface to the user, and transmitting embedded control information to inexpensive sensor units integrated with the devices. To use PICOntrol, the user points the handheld projector at a target device, overlays a projected user interface on its sensor unit, and performs various GUI-style or gestural interactions. PICOntrol enables direct, visible, and rich interactions with various physical devices without requiring central infrastructure. We present our prototype implementation as well as explorations of its interaction space through various application examples.