This is an automatic bubble ring maker

Its a clever mechanism that produces a bubble ring every few seconds.

Air fills the underside of the device, and when the buoyancy of the air overcomes the weight of the flipper the lever flips up and releases a blip of air that forms a bubble ring.  

Print Settings
Printer brand:
Ultimaker

Printer:

Ender 3 v2 neo

Rafts:
Doesn't Matter
Supports:
Yes
Resolution:
.2
Infill:
20%
Notes:
The only piece that needs support is the airline inlet. If you have Cura use the block support tool to make sure there is no support in the air inlet.