I made several feeding rings with auto-level support to accommodate water evaporation. The support can be used with an air-tube suction cup.
You can use it around your floating plants to feed your fish or, as I do, to keep just a small amount of floating plants inside the rings.
Use three walls and 0% infill to ensure it floats.
The author marked this model as their own original creation. Imported from Thingiverse.