This is one of those toys that you whirl around on a piece of string and it makes a chirping sound like a flock of sparrows. I have no idea what they're called, so I called it birb_chirper.
This is a thin-walled model, so use at least two shells and no infill for smooth walls.
Take a piece of thin string about 1 metre long (I used micro-cord, very fine paracord), pass it through the hole in the tip, then tie off a jam knot that's big enough to stop in the hole in the top but still pass back through the slot in the side. Now whirl the thing around fast by the string, and it should start to chirp.
This is intended for the amusement of small children and the annoyance of adults.
The tip of this thing is an ogee curve. I've included my library for creating simple ogee and ogive profiles.