I built a Corsi-Rosenthal box

It's easy if you follow the instructions, so of course I went rogue and made mistakes. I'll explain them here so you don't have to make the same ones. :) I apologize in advance for the imperial length measurements. That's what we have available in stores in the USA, even though I'd much prefer switching to metric.

The design concept is sound, and it's even supported by 3M which makes Filtrete brand filters.  If you really need to cut costs, then you can create a triangle or prism design with only 2 filters instead of 4.  The upward-pointing box design has better air flow filtration, though.

( Read how I did it... )

It's a good use for some of the birthday money that my parents sent me. I went shopping for parts on the same day I deposited that check. Happy Birthday (tomorrow) to me, with a fun Build-It-Yourself adventure (today).