Please also check out my latest whistle designs:

Very loud dual-tone whistle
I needed a compact and loud whistle to fit my keychain and couldn't find any design which fits my requirements. What I found was either too bulky, too fragile, or too quiet.

So I made my own design, and this are the key advantages:

• extremely loud for it's size,
• very compact, only 5 mm thick, 14.3 mm wide and 48.9 mm long,
• double tone, sounds similar to a referee's whistle,
• easy to blow,
• sturdy and hard to destroy,
• lean design,
• easy to print,
• fast printing (< 20 min), little filament required (approx. 2.5 grams).

How to print:
Use a line width of 0.4 mm and a layer height of 0.2 mm, 4 top layers and 4 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 image above (the white dots represent the Z-seam). Use the “Z Seam Alignment: User specified” option in Cura or the "Seam Painting" option in PrusaSlicer to achieve this.
If you are using Cura I recommend V4.13.1 for this design as Cura 5.x still has problems placing the Z-seam.
Print slowly to achieve sharp edges.
If you want a multicolor print as in the picture above, change filament at the desired height.

Do you like it?
If you have printed this design and you like it, I would be happy if your make is uploaded.