I am in a situation that requires me to have a map that contains a layer of bedrock, two layers of air, and five or so layers of bedrock respectively. Just having a normal flatland world would be incredibly boring, and it would be much more entertaining to have a world with mountains, oceans, deserts etc. When I say mountains, oceans, and deserts, I do not mean just the biomes, but the physical part as well. This previously mentioned collection of layers does not have to be on the very bottom of the world, but it needs to be near the bottom of the world. Any assistance is greatly appreciated.
How would I make a world that has a layer of bedrock at the bottom, two layers of air, then 5 layers of bedrock, and still have normal terrain on the top such as mountains, oceans etc. or take a standard world and add the previously mentioned bedrock, air, and then bedrock as previously mentioned.