Bubble builds in Fortnite are created using a specific set of materials and techniques. The first step is to find a good location for your bubble. It should be high up on a hill or mountainside so that it has a good view of the surrounding area. Once you've found the perfect spot, start building your foundation. Use metal walls and floors to create a strong base for your bubble. Then, add in windows made of glass blocks so that you can see out from inside your fort. Finally, top off your bubble with a roof made of either wood or metal.