Room Air Filter

What is this

A cheaper (and parametric-ish) air purifier compatible with a range of air-filters, capable of 

Why is this

Room air purifiers are usually quite expensive for something that is basically a fan + a (consumable) filter.
Also, each machine has its own specific filter, and first-party filter usually have an unnecessary markup.

I wanted a solution that sourced easily available parts and was compatible with a range of filters (diameter of 16 to 20cm with the default adapter)

The CAD file

I may update from time to time the files in this listing (last time I updated the files: May 5th 2026)
And I may create a repo on codeberg sometime in the future (if so, there will be a link there).

I used freecad for this project (fusion does not work well at all on linux), but it's available under the GPLv3 license. I'm very new to anything CAD and freecad is what it is. 

Bill Of Materials

• 1x 1kg roll of PLA / PETG / ... filament.
  Will only use around 600 to 650g of filament (in PLA's case. Density might affect this).

• 1x roll of TPU, optional-ish, is required for the filter adapter. I used 85A, but 90A should work as well (no idea about 95A tho).
  Less than 100g will be used (unless printed twice, which will use around max 150g)

• 1x air filter (cylinder, up to the max dimensions that the filter can handle. In the default case, 16 to 20cm in both diameter and height. Adapters can be printed as well)
  

• 1x 120mm fan (if you use the PWM controller, a PWM fan is needed)
  It will work with any 120mm fan you have laying around, but will works best with any high static pressure fans, like the noctua NF-F12 IndustrialPPC. (the NF-P12 redux works as well, but has limited airflow as the fan static pressure is not high enough).
  A very important note: High CFM will not translate to high airflow when the filter is present, as the filter has a high impedance. The fan must have a balance of static pressure and airflow to achieve the best results.
  
  Fan should be 120mm x 120mm x 25mm by default, but the CAD file has a parameter for the height of the fan. Keep in mind that fans above 25mm will not focus on silence.
  
  Fan cable length should be around 25cm (max-filter-height + ~5cm).
  

Optional, but may require designing a (single) custom piece if opted-out:

• 1x USB-C 12v module (5W should support all the reasonable 120mm fans out there)
  Dimensions in the exported 3mf files are for boards around 10-11mm x 20mm
  I use one very similar to this one: https://www.aliexpress.com/item/1005010406732928.html
  

• 1x USB-C adapter that can do 12V (you probably have multiple of them already)

• If no USB-C power board, any form of 12V/0.5A (or 12V/1A) power input, but with a custom part design.
  A step file is provided for this purpose.

• 1x Fan PWM controller optional, but allows to change the speed of the fan and usually provide a way to plug the fan.
  I use one very similar to this one: https://www.aliexpress.com/item/1005004904458737.html
  

The cost

Prices are in CAD, and I will assume the worst case (if it's a bundle of 5 pieces I will count the whole price instead of dividing it by the number of pieces). 

• USB-C board + fan PWM: around $15 (CAD). 

• Fan:

  • Noctua NF-F12 industrialPPC: $45 (CAD)

  • Around $25/$30 (CAD) for a fan with high enough static pressure

• PLA + TPU:

  • worst case, 1kg roll each: PLA: $15 (CAD), TPU 90A: $40 (CAD) 

  • ratio with overestimated usage for TPU: $6 (CAD)

•  Filter (consumable):  $40 (CAD) for a pack of two HEPA+Carbon filters, or whatever is compatible and offer the best quality/price.

The cost ranges from $75 (CAD) to $100 (CAD) + price of TPU depending on the fan. Commercially available off-brand air filters of the same size (~20cm diameter filters, high CFM) are around or above $120(CAD) and are locked to a specific filter size.

Build Instructions

Coming soon :)