This is a traditional bird whistle based on an old toy. Print and fill it with water up to 50-70% of the height (just play with the water level).
Blow the whistle gently and rock it back and forth to change the tone. The hole in the head can also be partially covered for changing the pitch.

Creality

Ender 5

No

Yes

0.2 mm

20 %

I recommend printing the whistle leaning on one side. Any infill (pattern and density) should work, since the model is most solid walls. Use a good number of top and bottom layers for better water seal. The first top layers are supposed to print on thin air, so make sure you have good bridge settings.
Use supports only touching the buildplate, so the interior will be completely hollow.