Good old dwarven work.

Prerequisites: Craft (Weapons and Armors) Ranks 10

Benefit: You can create magic weapons, armor, or shields. Enhancing a weapon, suit of armor, or shield takes 1 day for each 1,000 gp in the price of its magical features. To enhance a weapon, suit of armor, or shield, you must use up raw materials costing half of this total price. You may only add enhancement bonus to a weapon, but unless you aquire the ability to cast the required spells to create special abilities. The weapon, armor, or shield to be enhanced must be a masterwork item that you provide. Its cost is not included in the above cost. You can also mend a broken magic weapon, suit of armor, or shield if it is one that you could make. Doing so costs half the raw materials and half the time it would take to craft that item in the first place. You craft at a caster level equal to your own level + 1 per 10 points of craft weapon and armor.