After a lot of fine work and countless test prints, I proudly present the first reliably functioning 3D printable Ultrasonic Whistle. With a powerful blow, it breaks the barrier of 20 kHz that separates ultrasound from “normal” sound.

You'll probably think that this whistle isn't working - but that's because humans (especially as they get older) hear higher tones less loudly or not at all - unlike many animals! I therefore recommend a frequency measurement app for testing. I use this android app.

WARNING:
This whistle is not a toy! It's very loud which can harm the ears, so please protect your ears and don't use it near other people or animals!

How to print:

First of all: this whistle has very small structures inside - corresponding to the short wavelength of ultrasonic sound. For successful printing, your printer should be well calibrated and work precisely.

Use a line width of 0.4 mm and a layer height of 0.2 mm, 8 top layers and 8 bottom layers.

The whistle requires correct positioning of the Z-seam - it shouldn't be placed in the narrow air passages inside the whistle. The Z-seam should be positioned as shown in the last 2 images above. Use the “Z Seam Alignment: User specified” option in Cura or the "Seam Painting" option in PrusaSlicer and Bambu Studio to achieve this.

If you want a dual color print, change color at layer 29.

Print slowly to achieve sharp edges!