How to create "On Drop" function on an item so that this item can awso later recognize what exactly is dropped on it (for crafting) ?

[Everynone]

@catz111

a simple solution

With stacks of inventory items? This is never simple, actually. Inventories + crafting is generally convoluted. Hence the plethora of tuts of varying quality. Avoid comparing strings. Use sets if crafting table does not require repetitions.