This doesn't include collecting the base materials, or smelting, just the actual crafting process itself. For example, a cake requires two steps, as you have to craft three buckets for the milk, then combine with the wheat/eggs/sugar. A minecart with hopper requires 4 steps, as you have to craft the chest, the hopper, the minecart, then the minecart with hopper.
Is this the most complex crafting recipe, in terms of number of steps needed to craft? Or is there a recipe which needs 5 steps, or more?