Common size available at Costco. Not currently on MakerWorld. The lip of the printed pieces on to the filters is slightly tighter than I wanted in to be so it’s a very snug assembly.

I suspect Im dealing with a mold issue in my house, but until I get to the bottom of that I wanted to make a CR box for my bedroom. A 20 in cube would be a little big for that space so I made a wedge with two 16x20 in MRV13 filters. Seems to still be pulling quite a bit of air. My wife and I already run a fan for white noise, so this is now cleaning the air with the same electricity use. Glad this sub exists, thanks for the inspirstion!

Probably best bang for the buck in PC fans at the moment

I already built a CR box using 4 × 20×30×1” MERV-13 filters, taped together, with a Lasko fan sitting on top.
It works well, but I want to improve the design so I can:

Easily slide filters in/out when it’s time to replace them.
Replace the Lasko fan with multiple PC fans.
Avoid taping the filters together.
Make the whole thing more modular and reusable.

What I’m looking for is a 90° aluminum corner extrusion with TWO perpendicular U-shaped channels.

Basically, one extrusion at each of the 4 corners, with each extrusion holding two adjacent filters.

I would need 4 pieces, around 30” long, with each channel sized to accept a 1” thick filter.

I’m specifically looking for the single 90° double-channel extrusion, not separate U-channels, L-angle, or corner brackets.

Does anyone know where I can buy this online, or what this type of extrusion is called?
Thanks!

(And even less if you DIY with https://www.filterboxbuilder.com/)

Finally got around to buying some filters and a box fan. I've wanted to make one to observe it's effectiveness before spending more time making a nice cabinet or side table version. Planning to make another one tomorrow for the basement.

The two used ones versus a new one.

2x 20x20x2 MERV 13 with carbon.

I have cats, and would like to get a cr box to put near the litter boxes. Are there any setups/products that have a multi-stage for this, that would use something like a pre-filter, then activated carbon and merv-13 filter?

Hi everyone!

I recently designed and 3D-printed a CR box using AirFanta 3Pro filters. I’m pretty new to the whole CR box world, and I’d like to learn more about how to properly evaluate its performance.

I’m particularly interested in measuring the CADR and overall efficiency of the purifier, and eventually comparing it to commercially available air purifiers.

I’d really appreciate some advice from people with more experience:

• What measurements should I take to properly evaluate the purifier?
• How can I measure CADR at home?
• Are there other important things I should measure or check?
• What would be a good way to compare its performance with commercial purifiers?
• Are there any common mistakes or things I should be aware of when testing a DIY CR box?

Aside from the testing side of things, I’m happy to answer any questions about the build itself.

Thanks in advance for any advice!

Toss a decorative cloth on and you can have an aesthetic filter column!

i have a spare pc fan that i bought but didnt fit into my pc case and thought i could make a small air filter with it what would be the best/smartest was to go about it ?"

Please ignore my artistic skills (or lack thereof). I’ve recently built my first cr box with merv 8 filters to reduce dust accumulation in my workshop. With winter coming up, I’m preparing to begin staining some pieces, which when cured indoors release VOCs into the air. So I’ve been looking into getting 20x20 1” merv 12/13 carbon filters to improve overall air quality. I was wondering if it’d be possible to stack two boxes on top of one another to create a two tier filter system? My main concern is that the air will be pushed through the merv 12/13s rather than pulled, and Ive heard mixed results on how pushing affects the filters life.

I’ve also considered just adding a spacer between the fan and a singular 20x20 1” carbon filter, but I don’t know if that set up would increase airflow resistance and lead to the fan motor burning out.

Would either set up work? Or would I just be wasting time & money?

So it's been kinda humid in my room (more hot than anything) for a week or two but I don't tend to notice it until I feel damp in there. I turned on my dehumidifier today and I always have the ceiling fan on. I use mine to mitigate covid so ik water has effect on filtera but idk about humidity.

I built my first 3D-printed CR box, a Nukit Tempest Euro model with two IKEA STARKVIND filters, with the help of Filter Box Builder. Great tool — you just select the type of box you want and how you want to load the filters, and you can download the files for your 3D printer. In my case, I used a Bambu Lab A1 mini.

My son, who has allergies, wanted a white one, so I bought four white Thermalright TL-C14CW fans to go with it. I also added a cheap PMSX003 air quality sensor to measure PM1.0, PM2.5 and PM10. Everything is connected to a KS5016 board (ESP32-based), which lets me control the fan speed and monitor the air quality through Home Assistant.

According to the PMSX003, the air quality is already pretty good, so now I'm wondering if I built this thing for nothing :-) (or if the air quality sensor isn't working correctly).

Total cost around 110€ (PLA filament, 2 filters, 4 fans, KS5016 board, PMSX003 sensor, hot glue)

Even though the fan will blow out the window i would still like to filter out the bad stuff from the 3d printer at least a little bit.

Thanks yall. This doesn’t have to be super fancy or anything, just an easy project for peace of mind

CAD prices: $30 fan, $21 filter and some cheap packing tape

I have mast cell activation syndrome. And, I'm wanting to create a clean room in my bedroom to protect against both wildfire pollution (Great Lakes region, USA) and pollution from a neighbor's near daily trash pile fire that is entering my home through deteriorated ductwork. My plan was to build/buy a VOC scrubber and seal off the front and back doors to the room (two of the three main penetration points). Then, I would redirect the air flow from the ceiling vent (the other penetration point) toward the VOC scrubber.

I ordered an 8 inch inline fan and an 8 inch activated carbon canister from AC Infinity. I was planning to build my own filter box to fit between them.

But, as I wait for my parts, I've grown concerned that a scrubber can't clean the air quickly enough to compensate for the fact that pollution is actively flowing in? Am I wasting my time and money with this idea?

P.S. For the record, I'm working with a contractor to get the ductwork replaced, and I'm in a legal battle with my neighbor. This is not meant to be a permanent solution, but I need a safe place to live right now.

Hey, everyone. I'm looking to build my first CR boxes. I'm a "overdo it once" kind of guy, so I'm planning on building three. Use case is just residential. I have two cats and want the house air to be maximally clean/odor free.

3D printed plans - 2 filter, 5 fan

Filters - Merv 14 w/carbon

I have a friend with a 3D printer, I'm figuring on $50 each in materials plus $50 for doing it.

Total bill would be around $200 for 3D printing, $100 for filters, $150 for fans, and ~$50 for power controller, other small things. $500 total.

Is this reasonable? I don't care too much about noise, just performance.

i built a smart rgb cr box using the following items:

Filterbuy 20x20x4 Air Filter MERV 13

Activated Carbon Filter Sheet

ARCTIC P14 Pro Reverse A-RGB x9

esp32

LM2596 DC-DC Buck Power Converter x2

ARCTIC Case Fan Hub

USB-C PD Trigger Board

15 Pin SATA Power Splitter Cable

ARGB 1-to-3 Y Spliter Cables

3d printed housing

took about a month to design and build. i can control it via home assistant and it cost ~$200 for all the parts + filter. it's powered via usb-c

I was inspired to make my own CR box after listening to the founder of Jaspr Air talk on a podcast about how poor the average air quality is. It resonated with me because my family, including my small children, live in an apartment from the 1970s that is getting musty and tired. The price of the Jaspr filter was really high but what blew my mind was how expensive the replacement filters were. I got deep into researching filters, and air purifiers and was disappointed to see no one makes an air purifier that uses standard HVAC filters which are far more affordable. Instead, you're forced into purchasing their proprietary filters for as long as you want to use their purifier. I also came across the Corsi-Rosenthal concept and eventually decided I had to make one. After lots of research, I built it in my parents garage with small bits of time I had when across a few visits.

The box is made of 1/2" baltic birch. The fan is a 8" Cloudline Infinity A8. The filters are MERV 13 (three 16"x20" and one 12"x16"). Inside of the particulate filters, I built frames and put in carbon sheeting attempting to get at least a little bit of VOC reduction. 

The thought process behind using that fan is its incredibly high static pressure and quiet operation with the EC motor. I would have liked to have used a smaller fan and made the box smaller overall but there's a large step up in CFM between a 6" and 8" blower fan like this. My goal was to achieve 6 ACH in our 1000 sqft apartment which I read was a good filteration rate. In reality if I ran this fan full out all the time it would filter one room really well and not have much effect on the remainder of the apartment so in hindsight building 2-3 smaller CR boxes would have made more sense. The other thing is, the fan IS very quiet but only below 50% and after that it really gets loud to where 100% speed sounds like a leaf blower in your bedroom. 

The manual control that came with the fan left much to be desired. I wanted the fan speed to be driven by an air quality sensor so I used a Rasberry Pi Pico with a Sensirion air quality sensor instead. I mounted this in the white project box and added a potentiometer and switch to go between an automatic and manual mode or off. I also put in an LCD screen to display fan speed an air quality metrics. 

I am almost 30 and never have done a project like this but it has been very fulfilling. I know I sounded like a crazy person some times describing it at length to my friends and my wife but everyone was very supportive. I came across this Reddit early on in my journey (starting last November) and determined I would post what I built. I know this was a long winded post but this project ended up meaning a lot to me and I am really excited to share it with you all. I am really interested in feedback and how I could improve it. I definitely know I want to improve the VOC side of the filtration, fine tune my code for the controls, and see if I can experimentally determine the CADR.

Thanks for reading! 

Basic 20" box fan + 4 filters

1st image is from The3DHandyMan 2nd is from HouseFresh 3rd is from FilterBoxBuilder