For working in Rental App is possible to add Items as rent item, which you have in storages. Not all of them are intended for rent and thats the reason why you have ability to create Item before creating Rent Item. For more information about creating Rent Item, see How to create Rent Item.
Go to Search and enter Items.
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Note:
In case you want to rent this item, the field Rent Item situated in section Inventory must be turned on. If it's turned off, the Item can not be rented! In case when Rent Item Created is turned on, it means that rent item is already created from this item.