3D Printer Safety Shutdown - Smoke Detector

Have you ever worried about leaving your printer running for those long 20 hour prints? With a heated bed, hot extruder, and cheap power supply, there's a lot that could go wrong. I have worried about leaving my printer unattended and wanted an automatic smoke detection and shutdown solution. This post contains all the information you need to build a 3D Printer Safety Shutdown. I am not selling anything. This is merely the information needed to make your own printer shutdown device.

I recently became aware that there are now off the shelf solutions to do this same safety shutdown function. They weren't available before. If you would rather build your own, this Thing is a good start, otherwise see the update below with links to ready made products.

This solution uses an IOT Power Relay from Digital-Loggers.com which has an input that can turn the IOT Power Relay strip on or off with a low voltage signal. The IOT Relay also has a "Normally On" pair of receptacles and a "Normally