Get Blocks of a Wall

So I'm trying to create something similar to the Walls minigame which includes many blocks placed in a cross shape (like the picture below) and I would like to know the best way to store all the wall blocks in a list or maybe a map.

Example (open) Example (close)

 

I would personally store it in a custom object with 8 locations (for the corners of the cross) and the height.

 

8 locations? Could you give me an example?

 

Okay so I figured it out, I tried using Set<Cuboid> and it did work fine but I'm not sure if it is the best way to achieve this.

 

@MrGriefer_ feel free to think of an alternative. Let me know what you come up with