First, get a barrier that will be your door.
Then have a button stick out of the barrier.
the buttons properties should look like this.
Then Wire the Button to the barrier like this.
Add a checker device.
Configure the properties of the checker like this
Of course you can use any item you want as the key (even weapons).
Add an item granter device with the item you chose.
Configure the granter like this.
Add a Popup device.
Configure the popup like this.
Then wire the checker to the popup like this.
Then wire the checker to the item Granter like this.
The wire the checker to the barrier like this.
Then wire the checker to the Button like this.
Then when you have the item, you can open the door, then it deletes it, it you do not not the item to be deleted, delete the item granter.
So there! your quest maps are better now!