Why don't we ever see astronauts on space walks, or floating 'weightless' in the ISS, adjusting their orientation by rotating their arms like we do instinctively when about to lose our balance and fall backwards head over heels. Would it work? How about adjusting one's orientation by rotating a hand in a circle over one's head and/or moving a hand in a horizontal circle in front of one's chest and consequently one's body rotating the opposite way around a vertical axis? Or by twiddling one's thumbs for a very long time?
I'm thinking that conservation of angular momentum should make this work. It would be a great physics lesson to see it, if it worked.
Could a space ship be turned around by the crew running or walking in a circle inside it? How about by a crew member sitting on the outside of the ship and whirling a mass on a long string?