Our goal is to 3D print wireless sensors, input widgets and objects that can communicate with smartphones and other Wi-Fi devices, without the need for batteries or electronics. To this end, we present a novel toolkit for wireless connectivity that can be integrated with 3D digital models and fabricated using commodity desktop 3D printers and commercially available plastic filament materials. Specically, we introduce the first computational designs that 1) send data to commercial RF receivers including Wi-Fi, enabling 3D printed wireless sensors and input widgets, and 2) embed data within objects using magnetic fields and decode the data using magnetometers on commodity smartphones. To demonstrate the potential of our techniques, we design the first fully 3D printed wireless sensors including a weight scale, flow sensor and anemometer that can transmit sensor data. Furthermore, we 3D print eyeglass frames, armbands as well as artistic models with embedded magnetic data. Finally, we present various 3D printed application prototypes including buttons, smart sliders and physical knobs that wirelessly control music volume and lights as well as smart bottles that can sense liquid flow and send data to nearby RF devices, without batteries or electronics.