So, there was this thing in ProjectE, where all items had it's emc value (equivalent cost or smth) and it's was computed from sum of it's ingredients (some items had pre-written emcs, so pretty much all of items' values could be calculated from its crafting recipe). I want to do something similar: store an array in each itemStack of all ids of item's that was used to craft this item, default value is array, contining only current item's id and when items used in crafting (workbench only), product gains all data from ingredients' arrays merged. Example: if you find a iron ingot in a chest, its value should be "{"iron_ingot"}", but if you crafted an ingot into a nuggets, and then back, then it should be "{"iron_ingot","iron_nugget"}". Question is how do i store it, initialize it to every item and how do i generate it on crafting result?

Use NBT data to store the ID array. Initialize when the item spawns. Intercept the ItemCraftedEvent, merge the ingredient arrays, and write to the craft result.