Turning a case into an air purifier

Long story short I have bad allergies and was thnking of making a 3d printed fitting to the front of my case - then I saw this and was wondering if it was ever made. Really want to read a performance review. I understand it cuts down air flow but was wondering if its still tollerable or just a bad idea. If I do a 3d print one it will be the filter the next size up to 2 sp 140mm fans. 

  http://www.techpowerup.com/mobile/178510/silverstone-mammoth-mmo1-eatx-case-detailed-too.html

I have a Cooler Master 932 HAF ... and I am amazed at how much it filters ...  three 230mm fans move massive amounts of air ... I have to clean it monthly.... and I live where it rains alot.

i would think your filters would get restricted and need frequent changes

EDIT .. I forgot I also run an Oreck air purifier in the room to help ...

The filter I would use would be a few inches wider then the fans I would use .. So hopefully less restriction. I currently have a thermaltake chaser and a level 10gt both have those sponge like filters that do an OK job but I want to go beyond.

I'll be waiting for blackfriday cyber monday anyways to start making the mod.