The design accidentally came to my mind. I took my earlier acorn design as a basis.

The first test whistle turned out to be quite loud, but with each new iteration, it sounded worse and worse π.
In the end, I found the right shape after several iterations π .
This whistle is the type of design that cannot be partially printed. Moreover, if loved ones are nearby, they naturally get irritated by the constant testing of the sounds π.
I kept the cap, but it doesnβt serve any function other than being more convenient to print separately in brown. Something seems to be calling for attention under the cap β I think Iβll add something there later, as there is unused space.
Also, I made a version with an enlarged cap to make it look more harmonious.

This design is available on MakerWorld, where I posted it as an exclusive.
Magic Acorn Whislte:
https://makerworld.com/en/models/1214146-magic-acorn-whislte#profileId-1229632