If you are tired of smelling your beloved cat's litter box, this will solve your problems! The ambient air and odors from the litter box will be pulled through a carbon filter followed by a HEPA filter before being exhausted out the rear, leaving you with virtually no smell. As a byproduct of the filters your litter box will be less dusty, which is healthier for everybody. My wife and I have been using this design on our own litter box with really great results. The filters seem to last for quite a while, but your mileage may vary. Your nose will tell you when it's time to replace the filters!

This project relies on some very simple and easy to source parts for finishing. Aside from the printed parts, you will need:

4x M3 x 25mm screws
4x M3 x 30mm screws
8x M3 nuts
1x 120mm 12V computer fan (this does not need to be high-powered or noisy!)
1x 12V power supply
1x 130mm x 130mm carbon filter
1x "Eureka HF1, HF12, EL012 HEPA Filter, Part # H13, SP012, H12, 60286A, EL020 & EF26" style HEPA filter
1x hooded litter box

The parts can be printed in any material using any resolution, so don't fret too much about what is "best." As mentioned in the parts list, you will need a hooded litter box. We have been able to install this on several different styles, but the installation location may vary depending on the space available on the "hood."

Once you have printed the main parts and gathered all of the extra parts, the assembly is rather straight forward. There are a few noteworthy bits to highlight however:

1- One of the parts to print is a stencil that will aide you in cutting out the hole for the filter as well as drilling the holes to keep the assembly together.
2- There is a hole on the side of the middle piece titled "rear filter housing exterior" that is designed to run your fan's power cables through. This just keeps things looking tidy.
3- The order of assembly can be seen in the photos, but I did omit the air deflector. The correct order of assembly is "filter cover interior," filters, litter box hood, "rear filter housing exterior," and "air deflector rear."

This thing is currently in its infancy, and more revisions will follow. Some highlights to expect in the future are assembly with fewer screws and easier access to filters for when it's time to replace the filters.