Links to all the demonstrations from Ruben’s Toroidal Vortex presentation
Remember, air is not “nothing”. The density of air at 15 degrees Celsius at sea level is 1.225 kilograms per cubic metre. That’s a bit heavier than a litre of milk. This is why aeroplanes and helicopters can fly. If you built an aeroplane and a runway on the Moon and managed to get it moving at 300kph on the Moon, it still would not lift off because with no air flowing over the them, the wings would not generate any lift. The surprising density of air also means you can shoot groovy toroidal vortices around the place. And you can make them visible with smoke or fog. And you should.
Video of Ruben shooting fog rings at Dr Karl & Adam Spencer on Sleek Geeks this page includes instructions for how to make a toroidal vortex gun (you can use a cardboard box instead of a plastic bin)
Tumbelwing Gliders instructions for how to make and fly