Penne 2.0 – Public Domain Safety Whistle (CC0)

I created this compact, powerful safety whistle from scratch to be freely shared with anyone who needs one — no questions asked.

*Update 01-31-26 Added OpenSCAD files based on the work of User M_D_K
Link to Original file located hereThanks so much!!!! 

Penne 2.0 is a refined update to the original design, improved through real-world printing, large-batch distribution, and community feedback. The mission remains unchanged:

Turn quiet into the safety of sound.

What’s New in Penne 2.0

• Reinforced lanyard area
  Stronger top and bottom walls around the lanyard inlet for increased durability.

• Longer mouthpiece tip
  Improves airflow and makes it easier for more people to get a strong, consistent tone.

• Reduced weight: ~1 gram per whistle
  Ideal for bulk counting, weighing, and large-scale distribution.

• Improved plate layouts
  Merged whistles have been reorganized into fewer, more flexible groups.

• More reliable first layers
  The first millimeter of the print is slowed and stabilized to reduce early failures when printing many parts at once.

Why This Exists

Whether you’re boating, hiking, camping, running, training scouts, organizing events, or advocating for your own safety and voice, this whistle is designed to be there when you need it most.

This design is released as Public Domain (CC0).
You are free to:

• Print it

• Share it

• Remix it

• Distribute it

• Sell prints or give them away

No attribution required. No restrictions.

If you’re part of a community group, school, scout troop, mutual aid network, or safety-focused organization, you are encouraged to print and distribute these in bulk. These whistles have already reached tens of thousands of people, and they continue to spread thanks to makers around the world.

Files & Custom Layouts

All STL files are included below.

If you’d like a version optimized to maximize your specific print bed, feel free to message me with your printer dimensions and I can generate a custom layout.

Don’t Have a 3D Printer?

You can still get a whistle.

• Chicagoland area: anonymous local drop options available

• Worldwide: printing and shipping available via a partner service (paid option)

No questions asked.

Recommended Print Settings

• Nozzle: 0.4 mm

• Layer Height: 0.24 mm

• Walls: 2–3

• Infill: 100% (for maximum tone consistency and durability)

• Supports: None

• Material: Any

Tips & Bulk Printing Recommendations

Printing many small parts on one plate places extra importance on first-layer adhesion and printer tuning.

When printing in high quantities:

• Make sure your printer is well calibrated

• Use a build plate known for strong adhesion

• Keep your first layer slow and consistent

If you experience adhesion issues:

• Try a higher-grip build surface

• Use appropriate adhesion aids if needed

It’s recommended to start with a smaller batch, confirm reliability, and then scale up gradually. These whistles have been printed and distributed in the tens of thousands, but each printer setup is different — take the time to dial it in.

Turning quiet into the safety of sound.