You can buy small vacuum chambers on ebay. Making a large one is also doable. What's problematic is making one lightweight enough to be buoyant. When you make s

You can buy small vacuum chambers on ebay. Making a large one is also doable. What's problematic is making one lightweight enough to be buoyant. When you make staggered one it will still have too much mass because all shells will weight as much as one thicker shell.