This is a HEPA 11 air filter with activated carbon that can run on either 12v or 24v. It is to be used in a 3D printer enclosure.

I have an enclosure for one of my Prusas that I use for ABS, ASA, polycarbonate, etc. While the enclosure does a great job at keeping the heat and smell in, I can't help but notice the plastic smell when I open it up. I have no way of running a vent out a window since I work in the basement about 35 feet from the closest window. I had to find another solution.

So, in the spirit of owning 3D printers, I decided to design and build my own solution. I looked at filter cartridges that are replacements for air purifiers and found one I liked called the Airtory Air Purifier HEPA Filter Portable Air Purifier for Strollers. (I copied and pasted that from Amazon, not the best grammar!)

While this does a great job at reducing the smell, it should not be considered as something that will address any heath concerns that some people have with ABS, ASA, and other plastics. However, using this may be better than not using one, and does achieve my primary goal of significantly reducing the plastic smell. (Please see my note in my Final Comments below.)

The first two pictures are renders done in Cinema4D using the Arnold renderer. The next three pictures are an actual assembled unit. The next picture is the filter that is required. The remaining images are renders done in Fusion 360 to show the three prints.

Print instructions

There are three printed parts. One of the prints is the gasket, while recommend, is optional. The additional hardware needed is the filter cartridge, four M3X16 screws, and either a 12v or 24v 40mm fan. Additionally, you will need to supply power to this unit which can come from your printer or from an independent power supply.

The filter I chose to use can be found on Amazon. Search for B07SJ479NN.

Using The Included gCode Files
I have two gCode files prepared for the Prusa MK3/s printers. One file includes both the main body and the screw-on filter cap and the file is prepared for PLA. The second file is the gasket which has been prepared for TPU. While the gasket is optional, I just do not feel comfortable with any moving mechanical part attached to plastic without a gasket. But that's me, do what you want.

I also want to add a quick note about printing with TPU if this is something you are not familiar with. On your Prusa MK3/s you must release a lot of the tension on the extruder gears or you will have issues with the filament getting tangled around the BondTech gears. Also you need to keep in mind that TPU will adhere to the print bed, and the smooth print bed will really bond exceptionally well to TPU. That is why I would recommend either using the textured sheet, or some type of release agent on the smooth sheet.

Using The stl Files
Additionally, I have included three stl files. One is the main body, one is the screw-on filter cap, and the last file is the gasket. The parts are oriented for proper printing, just place them in your slicer. The body and screw-on cap can be printed in any material, just consider the temperature of your enclosure. I never go above 40C, so PLA works fine for me. If your enclosure temperature goes above that, then consider using PETG or ABS. The gasket must be printed in flexible material, I used TPU. This was designed to not use supports. A layer height of 0.15 or 0.20 is fine, with 15% to 20% infill.

Assembly
Insert four M3X16 screws through the 12v or 24v (your choice) 40mm fan into the main body, with the gasket between the fan and body. No need to over tighten as you may strip the holes. Please make sure the label on the fan is on the outside! Airflow is designed to come in from the filter and out the fan. There are many reasons I designed it this way, but one of the obvious reasons is to keep clean air going through the fan.

Next, insert a filter cartridge all the way into the large opening of the main body. Push the cartridge all the way in until it stops against the lip inside. The metal screen on the filter needs to be inside the body and the paper filter should facing outside. Then screw the cap on, all the way. A new print may be tight at first, but screwing the cap on and off a few times should loosen it up. Once tight, the cap has a ridge that will press up against the filter to hold it in place.

The last step is to supply power to the fan. You can attach it to an available 12v or 24v output on your main board, or just attach an external 12v or 24v power supply to the fan. Using an external power source may require some soldering. Not a big deal for this, but move onto another project if you are uncomfortable with this or don't know what you are doing.

Modifications
As I usually do, I have included the STEP file for this. Please feel free to make any changes you want since this is what owning a 3D printer is all about!

Final Comments
I will say this again: This is designed to reduce the smell of plastic from a print enclosure, AND NOTHING ELSE. While there are added benefits of the filter being used, it is only a HEPA 11 filter. A better solution may be to use a HEPA 13, but this would require a very large print and possibly a much more powerful fan. This print is designed to help remove the smell from using plastics (such as ABS and ASA) and not address any possible heath issues some may associate with 3D printing. While it may not keep up with the smell while printing with certain brands of ABS, it helps to leave the fan running for about 15 minutes after the print is complete. Besides, you need to let the bed cool down anyway.

NOTE: I would like to add that I read a study that said HEPA 11 filters can filter out more than higher rated filters because the air is being recirculated in the box (thus refiltering the air) and will capture more than HEPA 12 or higher. The reason stated was that higher rated filters have more resistance, thus passing less air. By recirculating the air through a lower rated filter will allow more air to pass through the filter. So in this study a HEPA 11 filter produced 27% cleaner air compared to a HEPA 12 filter. But I still stand by my earlier comments that this should only be used to help reduce the smell and not address any possible heath concerns of 3D printing!

Please let me know if there are any changes I can make to help improve this print. Good luck and have fun with your 3D printing journey!