Tinker crafting skill line. Learn engineering to build mechanical devices, gadgets, and gizmos of any kind.
This will also unlock a new ability skill lines. It will have active and passive abilities. When the crafting skill line is 35% mastered.
Give the dwarven gears item a purpose.
Similar to the engineering profession in world of warcraft combind with the engineer class in guild wars 2.
This will require new resource items to be added into the game dropped by the mechanical creatures and found in a variety of containers. More types of gears, springs, glass, coils, wires, refined metal, and spare parts which can be found and retrieved.
When 75% mastered and above then cosmetic/collectible items can be crafted.
It will be optional.