For irrelevant reasons a co-worker and I took a piece of fishing line, threaded it through openings of an air vent cover and tied balloons to each end.
Each time the heat kicked on the balloons would rise from the floor and begin bouncing off of one another. We noticed that they always hit each
other in approximately the same areas. It seemed as if they were battling.
So we decided to tape paper clips, with one end bent out horizontally, to each balloon and bet on which one would outlast the other. To our surprise it took over a week of dueling to get a winner, but they fought well, frequently hitting their targets.
We decided to try this with different balloons on different vent covers only to find that they didnt work as well on ceiling vents and that the measurements for spacing and length of line was important and required too much tweaking to get another game started.
So I suggest we make a light weight magnetic device that will attach to the vent cover, floor or ceiling. It will have lines with clips on the ends for attaching the balloons and be shaped so as to cause the air flow to result in attached balloons to consistently bounce off each other in approximately the same spots.
We then will pick our favorite sports team balloons, or political candidate, or just hero and villain balloons, and then attach our weapons, paper clips work well, to the spot of our choice, place our bets and let the game begin. I think this could be a fun game for home or office. Probably office bets would be more popular, at break times of coarse.
BTW my red Cardinal won against a white Knight in the first and only game in known history. I can't wait to put the political candidates up for a duel, best of three for a small wager and glory.