philipn / Corsi-Rosenthal Cube 49599639c5fa2b4a50fec170559e330f61b20287

The Corsi-Rosenthal Cube (sometimes called a Comparetto Cube) is an inexpensive, do-it-yourself air cleaner that can be easily constructed out of a box fan and MERV furnace filters.

Construction guide

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The Corsi-Rosenthal Cube (sometimes called a Comparetto Cube) is an inexpensive, do-it-yourself air cleaner that can be easily constructed out of a box fan and MERV furnace filters. The Corsi-Rosenthal Cube can give whole-room air cleaning performance comparable to commercial HEPA air cleaners that are 10x (or more) of the cost.

Construction guide

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Variations

5-filter version

Rather than placing a piece of cardboard on the bottom side of the cube, another filter can be added.  In this case, you would want to raise the cube off the ground (without blocking the entire bottom filter) so that the bottom filter could be utilized.  This would in theory lead to even less resistance on each of the filters, potentially prolonging the life of the cube or increasing the air output.

Two filter "wedge" design. 

A variation of the air cleaner can be made using two MERV filters (add details). This version is slightly less expensive (2 less filters are needed) and has a slightly smaller footprint.

News / media stories

• Could a Janky, Jury-Rigged Air Purifier Help Fight Covid-19? - Wired article on a simple, earlier version of the DIY air cleaner which uses a single filter taped directly to the back of the fan.