I would be nice to have gates for fences and doors for building and dungeons.
For gates, it could be 2 iron ignots for hinges on left side and 4 sticks.
For doors, it could be 2 iron ignots for hinges on top and bottom left side the 6 peices for what you want to make the door of. 6 planks for wooden door. 6 iron ignots for steel door
The only hard part would be programing and keeping track the state of being either open close. Right click to toggle.