One way to make something is to pre-process all the inputs. Make sure that you've worked the supply chain so that the raw materials are precisely the same every time. Guarantee that the working conditions are identical. Isolate all your processes from the outside world, so they're reliable and predictable.
The other way is to use natural light. Take what you get. Make the variability in your inputs part of what you create.
If you need to control your conditions, by all means, control them. Own that. It costs a lot and you need to make it worth it. It's foolish to expect that you can regularly wrestle variation into perfection without tools and effort. This is how modern surgery is done, and it's a good thing. Hospitals don't hesitate to invest time and money in controlling every element they can control.
Or, take the path of natural light. Embrace the idea that the conditions will never be ideal, which of course makes them always ideal. Because the thing about natural light is that whatever it is, is.
You can make this choice about the way you make ketchup, your hiking & camping methods or the way you do photography. Less equipment, less repeatability, more engagement. HT Paul.