Spin a thin-walled tube until the outward force of the spinning walls equal the pressure of the surrounding air. Simultaneously pump the air from the tube, creating thin-walled vacuum vessel with balanced forces on either side of it. This would generate lift, so you could make it into an airship.

Posted by ursois@reddit | CrazyIdeas | View on Reddit | 0 comments

The bigger the tube, the slower you'd have to spin it, so it scales up really well.