Power Armor Displays or a
Red Rocket Collection.
According to the patch notes that was uploaded in the game's webpage, players can visit Weapon and Armor Workbenches and open the
Modifiy menu to start the crafting process.
The system itself can yield a one-star, two-star, or three-star rated Legendary items, which can be upgraded or downgraded through the same crafting system, either by a different n-star item or an item that has the same star as the Legendary item, in case if you want a stat re-roll.
For example, a 3-star Legendary item can upgrade a 1-star item into its 3-star version with 3 random attirbutes, while a 2-star Legendary item can downgrade a 3-star item into its 2-star version with 2 random attributes.