Your digital wardrobe shelves
Technically speaking, shelves are results of saved filters or searches. If you turn filters off or change search conditions, the shelve's contents will change accordingly. When there are items you want to save that have no common criteria (type, color, brand), you can always attribute a common tag to them, then sort items by that tag and save them in one shelve.
Please note that the item data base is a whole. If you delete an item from a shelve you had created, it will also be deleted from your wardrobe, and not only from the shelve.