Shoot rings of air up to 30 feet and blow out candles or just annoy people with harmless air rings. Also possible: Using smoke to see the air rings. You may check on Youtube for "AirZooka". This one here is the same prinicple, but smaller.
You are going to need a ballon which needs to be cut in half.
After this itn needs to be pulled over the airzooka's bigger end
and be fixed with the ring. Look at the pictures for further reference!
Print it with the small end facing down and use supports for the handle.