You want Assemblers, Chemical Plants, Refineries and Furnaces that upgrade with more Items produced and smelted?
This is the mod for you.

Factories and Smelters gain higher levels with higher production count, the level is individual per entity.
Higher levels mean (can be disabled individually) * more crafting speed * more energy usage * more pollution * more modules slots * more productivity

Assembler 1 -> 25 Levels, upgrades to Assembler 2 after 25 Levels
Assembler 2 -> 50 Levels, upgrades to Assembler 3 after 50 Levels
Assembler 3 -> 100 Levels

Stone Furnace -> 25 Levels, upgrades to Steel Furnace after 25 Levels
Steel Furnace -> 100 Levels

Oil Refinery -> 100 Levels
Chemical Plant -> 100 Levels

Produced items get stored in memory when deconstructing factories and furnaces and are reapplied on building, so you do not lose those precious levels on refactoring your factory.

All aspects of the mod are configurable via mod settnings. Dont like leveled up assemblers using more power? Disable it! Dont like the progression curve? Change it!

Please report any bugs and suggestions here: https://github.com/renoth/factorio-factory-levels

Support mods for other mods:

Bobs Assembly Machines: https://mods.factorio.com/mod/bobassembly-levels