Minecraft wiki entry for Shelters, associated text: The best material to construct these are stone, stone brick or brick. Obsidian is harder to obtain but a lot better than stone-based blocks. They should be at least 4 blocks high and 2 iron doors for the exit. Make sure to build ramparts and cover walls, and fill with lava/water. Also have a 1×1×1 moat of lava/water with a torch in front like this: