ROBO COOKER. A PID controlled universal heater for steel parkerizing

I demonstrate how to make a PID controller which can be coupled to a small hotplate for accurate control of temperature when heating solutions for steel parkerizing. However it could also be used to heat glues, anodizing dyes, tempering of hardened steel or chocolate! It's a low cost solution requiring a cheap PID controller, a solid state relay and a K type thermocouple. These can be purchased as a kit on Ebay. The rest of the hardware is probably kicking around in your scrap box.