3D Guardian is an ultimate 3D printer fire prevention device, with some extras.

The primary function of 3D Guardian is to constantly monitor the printer's environment, and to shut it down (sounding an alarm) if the environment moves beyond the trained range. In addition to the traditional sensors (temperature, smoke, CO), it has a unique feature - a heated bed resistance sensor, which constantly monitors the resistance (voltage and current) of the heated bed wiring. Problems with this wiring (bad connectors, broken wires) is probably the most common cause of 3D printer fires; all these issues will manifest themselves as an increased bed wiring resistance, and the printer will be shut down automatically way before the actual fire starts.

The secondary function of 3D Guardian is to control the exhaust system of the printer's enclosure. That includes operating the air inlet and outlet (with stepper motors), and PWM control of the exhaust fan.

The device can be operated directly (5-keys keypad + 2x16 LCD screen), or via WiFi from a smart phone. It uses standard smart home frameworks (MQTT and OpenHAB), and can be easily integrated into your smart home setup.

Some experience with DIY electronics is required.

The printable parts are the parts for the control unit (3d_guardian_top, 3d_guardian_bottom, one red_button and five copies of the black_button), and for the power unit (Power_unit_top, Power_unit_bottom, Power_unit_part). Both original (SketchUp) and STL files are provided. I printed everything in ABS with 100% infill and 0.2 mm layers.

Full details (including the user guide) can be found here: http://pulsar124.wikia.com/wiki/3D_Guardian