Box Fan Air Filter Adapter for Wildfire Smoke

Design preview. Rendered from the file, not a photo.

The maker says it fits: Lasko 20 inch box fan. See the proof

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What it does

Turns a 20 inch box fan into an air filter for the home
Pairs with a standard furnace filter you already own
Saves hundreds vs buying a true HEPA unit
Brings cleaner air to homes during wildfire smoke

Build a real air filter from a box fan. This adapter clips a standard furnace filter onto a 20 inch box fan, so the cheap blower you already own pulls smoke and dust out of the air. A practical fix during wildfire season or hard renovation days.

The clips hold the filter against the fan intake without tape. Slide a fresh filter in, swap when it gets gray, repeat. Pair with a true HEPA filter for the best results, or use a cheaper merv-rated filter for general dust control.

Built for households dealing with smoke, allergies, or seasonal dust. The kind of fix that turns a scary news cycle into a manageable week.

4.9k downloads in the maker community. That is interest in the design on the site it came from, not our sales.

What it fits

The maker says it fits: Lasko 20 inch box fan

That is the maker's word, not a fit we measured. Check the size below against your own.

Lasko 20 inch box fanFrom the maker's own listing title, checked 2026-08-13. See the original post

Brand names here only say what this part fits. We are not connected to those companies, and they did not make or check this part.

What you get

This design prints as one piece.
Nothing else to print or buy for this to work.

What it is made of

Designs like this print well in PLA. Compare the materials.

Printed plastic is strong for its size, but it is not metal. We have not load tested this design, so we do not publish a weight rating. Keep it out of a hot car and away from open flame.