Show HN: I built an under-the-door fan duct to lower bedroom CO2

  • Posted 3 days ago by bizzz
  • 62 points
https://www.lepekhin.com/2025/06/22/DIY-Door-Fan-to-Fix-My-Groggy-Mornings
Hi HN,

This is my attempt to fix groggy mornings by lowering my bedroom CO2 from 1700 ppm to ~900 ppm.

I designed a simple, 3D-printed fan duct that directs air under the door to improve air circulation.

A note on the design process: I used CadQuery, a Python library for creating parametric 3D models. I didn't know tools like this existed and highly recommend it if you can program; it turned out to be more convenient than manually iterating on prototypes in a GUI.

The project is open source and the post explains the full build. Happy to answer any questions.

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