Skeletonizing, also known as sculpting the movement, is one of the finishing touches that many watch lovers pay pretty pennies for. Many watches do not show the skilled manual movement, leaving the art of sculpting unknown to the naked eye. Skeletonized wristwatches emphasize all the virtues of the luxury mechanical watch, displaying traditional craftsmanship and precision to the masses. 
As one might imagine, this kind of craftmanship takes the watchmakers innumerable hours. 5180/1 will be made each year. Patek Philippe, like other creators of true skeleton watches, warns all potential buyers that they will have to be prepared to wait with patience if they want to own a Skeletonized watch. As a bonus, the intense hand-work involved means that each watch will be unique.