Also, maintaining vacuum is probably easier in larger units since the volume is increasing faster than the surface area. More gas intrudes, but there is much mo

Also, maintaining vacuum is probably easier in larger units since the volume is increasing faster than the surface area. More gas intrudes, but there is much more space for it to intrude. The wildcard is what has to change for the thickness of the shell as it scales. That either makes it work, or be infeasible. More research required.