Haringod

I wonder if he finished it or not. The simplest and most straightforward approach is to consult the manuals for popular PID controllers such as the REX-C100 or the OVEN series (TRM10/TRM101/TRM210), which already include ready-made wiring diagrams. In general, it always comes down to one thing: the sensor is connected to the controller’s input, power is supplied separately (usually 220 V or 24 V), and the controller’s output goes to a relay or solid-state relay (SSR), which then controls the load, such as a heater. The main thing is not to confuse the sensor and power terminals and not to connect a high-power load directly to the controller.

You're already on the right track: if you have heating elements, thermocouples, and a PID controller, then most of the hard work is already behind you.