Earliest control panel?

Chemical manufacture started about 4000 BC with stuff like glass, bricks, …

I would hazard a guess that one of the first control panels showed up in one of those chemical plants.

Watching the color of a flame during (say during copper smelting ) and adjusting the air or fuel, counts as a control panel to me. Or a chemist watching the level of a reactant in a glass cup and adding stuff to maintain level counts as a control panel to me too.

Anyplace, where there is an observed parameter that is being controlled by humans by manipulating an input parameter, counts as a control action to me. If the observation is visual, then it’s a control panel : that’s what I am thinking.