Craft 5 items.

Crafting items includes making armor/weapons via Haedrig, or combining gems via the Jeweler, which is the much easier route to get this with little hassle. The gems required for this will drop from enemies as your progress through the game, and the items required to build equipment can be salvaged at the blacksmith (Rare items or above) or lower level materials can be upgraded in a similar way to how gems are combined.