How to create a key
This tutorial is going to example how to add a key to your blueprints as they are not included by default. Credited given to Kal_Agrim from the Bioware Boards as he posted the instructions there.

The first thing we need to do is to go to the Items tab, which is located in your Blueprints.

Next we need to create a new item, click on the "Items" tab in the Blueprint Menu to bring up all of the items in the game. Right-click anywhere in the New Item field to bring up a small pop-up menu: within that menu, go to "Create Blueprint," and select "Module" (this is unless you wish to create an item usable in any module: if you want to do that, select "Global" instead). This process creates a new item template for you to work with within that particular module group.

You will now see "item1" added to your blueprints:

Now left click on item1 so that it is selected and we need to amend the properties:

The fields that you need to change are highlighted in red.

    Icon: This is the icon that is displayed in the players inventory, you can choose from the following: "it_key_fancy", "it_key_complex", "it_key_black", "it_key_brass", "it_key_wood", "it_key_iron", "it_key_stone".
    Base Item need to be changed to key
    Resource Name - the name of the actual file on disk (the official filename of the item)
    Localized Name - the name of the item.
    Localized Description - base descriptive text for the item: this appears on normal items, or unidentified items before they have been identified.
    Tag - name by which an object can be referred to in script [Note: the tag, Resource Name, and Template Resref are all usually the same name, to keep things simple]. It is generally best to use unique tags, but unlike resrefs, two items can have the same tag.
    Classification - how the item is ordered within the toolset. Look at the Classification of other items and if you want your item to be included in the same Category then use the same classification number and do not forget to include the curly brackets.
    Localized Description (when identified) - descriptive text for the item after it has been identified.

Now we can place the key in a chest and test it in game. When a player opens the chest they will see the following: