As an Arcane Maester, you can craft magic items.
Crafting Magic Items
You can use the Overnight Crafting benefit of your Expert Crafting feature to craft magic items. When you craft a magic item, the maximum cost in GP increases to your Craftsman level times 25.
The Magic Item Crafting sidebar details the magic items you can create, specifies the Craftsman level you must reach to create each magic item, and shows the cost in materials an item will require. If a magic item incorporates an item that has a purchase cost (such as a weapon or a suit of armor), you can either enchant a nonmagical version of that item for no extra cost or craft the item wholesale, adding half of that item's cost to the cost in materials.
Magic Item Limitations
You can craft any number of magic items from among those available at Craftsman level 3. You can craft 5 magic items from those available at Craftsman level 5, 3 from among those available at level 10, and 3 from among those available at level 14. In the process of creating a new magic item, you can choose another magic item you have created and render it nonmagical to build a new one from the same category.
Save DC
If a magic item you use forces a creature to make a saving throw, you can use its DC or the following calculation: 8 plus your Intelligence modifier and Proficiency Bonus.
The following lists show which magic items you can create, the craftsman level you must have, and the cost in materials each item requires.