We are discussing a mod idea: to pack a large number of equipment into a huge black box of the manufacturing machine to save a lot of UPS.
I thought maybe a modification to the factory mod could be considered.
1. Build a factory building and install machines inside. It is required that the liquid must be transported in barrels and come out empty barrels.
2. Turn on a switch with a combination of keys in the factory building
3. The factory will calculate the incoming materials and output materials in the next period of time.
4. After the countdown is over, the plant changes the way items are brought in and out, and changes to a state where materials are destroyed at the designated location A and generated at location B.
This does not involve recipe modification (so no need to restart the game), and does not require humans to manually enter the recipe (if they do it manually, they will want to cheat). It is also possible to turn the factory building into a unit that does not consume UPS
The difficulty is:
1. Is it possible to realize the statistics of the incoming and outgoing materials of the plant?
2. Is it possible to use variable scripts to operate the external boxes of the factory building?
So I came to ask the mod author whether the above idea is feasible in principle.

I've thought about this idea for a long time, but it is much too sensitive to external conditions to be viable, and also too easily exploitable.

Suppose you build a factory building, start the test run, but the factory's output backs up. Since most of the produced items are stuck inside the factory building, the factory is registered as extremely inefficient.

Suppose you build a factory building, start the test run, but the factory's input is slow or dries out. This time, the factory is registered as efficient but extremely slow, and would not be able to speed up if the input increases.

Suppose you fill the factory building with only a large amount of chests full of steel plates, then let them belt out at full speed during the measuring phase while sending in a token amount of iron plates. The factory is registered as being able to turn each iron plate into thousands of steel plates, making it essentially an infinity chest for steel plates.

Unless you see a way to mitigate these cases that doesn't cause even more problems, this idea is unfortunately not viable.

So you're saying that the very structure of the game doesn't prevent us from packing a plant like this to save UPS. The problem is that cheating can't be prevented so that it's less fun, isn't it?
In fact factorio has a lot of cheating mods, if players want to cheat, there is no way to stop them.
The idea of packing the factory buildings will make it possible for us to break through the limitations of UPS and build a production line of extremely considerable scale.

Yes, that much is clear, abstracted factory buildings would be a huge boon to possible factory scales, but "running a factory building for a while and measuring the inputs and outputs" is just not a good way to implement this.