Mafuchit - Modular Air Filter Using Cheap Ikea Things

This is Mafuchit, the Modular Air Filter Using Cheap Ikea Things! I found the cheapest HEPA filter around, and made a modular in-line filter box around it so you can filter out particulate matter from any aerial sources, such as your 3D printer. Ikea also have options for activated charcoal filters, so I grabbed one of them to allow for VOC filtering too. Combine these cheap consumables with around a kilo of cheap filament, and some off-the-shelf air ducting, and you can clean all the air from your FDM or SLA 3D printer, laser cutter, or anything else besides!

This can be printed on any printer with a build plate at least 250x210mm in size (potentially smaller printers if you are prepared to cut panels in your slicer and glue them together), and is printed in multiple panels and assembled to give the best quality part with the lowest chance of a print failure scrapping the whole thing, and allows you to modify this to suit your needs later down the line if needed.

I've made a whole video covering a lot of why and how, so check it out!

Build options - Mafuchit Core (Slash and Backslash variants)

Mafuchit uses Ikea Uppatvind HEPA filters as the consumable filter. This is a 25x20x2cm HEPA filter that costs £3 and lasts up to 6 months, allowing for a significant amount of particulate matter air filtration for an extremely low cost. 

Each Mafuchit main section consists of six printed parts: 1 lid, 1 base, 2 sides and 2 in/out panels. The two variants are “Slash” and “Backslash”, and this is how the HEPA filter is arranged inside Mafuchit when you look at it with the lid removed. This can help with picking your lid choice if you want a window (more on that in a bit) but otherwise it doesn't matter which you go for just stay consistent!

There are options for the lid with writing that help you know what consumable filters you need and how often to replace them so you don't need to second-guess when it comes time to replace them, and a space to write when you replaced the filter last so you can stay on schedule. The MMU text version is easily doable with a single manual change as the text is only 0.2mm deep. That's how I printed mine in the pictures! But there is also a version with recessed text if you want the text with no filament change.

There is also the option to embed an acrylic window into the lid, which will allow you to see the HEPA filter and how dirty it is to give that extra reminder to replace it. I'm pretty forgetful so this helps me keep my air breathable. Check the BOM for the size, and make sure you read the printing instructions or watch the video to get the best result!

The side and base panels have options for wall mounting using screw hooks - that is, using 4 screws in the wall that you can securely hang Mafuchit from. Screw pattern is in the part list for each relevant part.

Build options - Common parts (In-out panels, section spacer)

The in/out panels are sized for 100mm/4" air ducting hose, but STEP files are included if you wish to make alterations for a different size hose. There are also versions that allow you to add any standard 120mm or 140mm PC fan or filter. I'm using this for a (large) dust filter - please note some axial fans may not have enough static pressure to overcome the filters!

There is also a section spacer. This is to allow you to attach add-on components to Mafuchit, such as…

Build options - Carbon filter add-on

HEPA filters only filter particulate matter. For VOCs (Volatile Organic Compounds) we need activated charcoal filtration. Ikea's disposable HEPA+carbon filters are significantly bigger than the Uppatvind HEPA filter and would have made Mafuchit unprintable on many printers (including mine), and £15 every 6 months (for both consumables) adds up. They also sell Nyttig Fil oven hood washable charcoal filters. These last 3 years but need washing every month. 

I picked the Nyttig Fil 559 filter for use, which costs £30 and fits the dimensions of Mafuchit very well. However, as Mafuchit is modular you can most certainly make your own remix for different charcoal filtration, either as a different cartridge for this add-on section or an entirely different add-on section instead. In fact I would encourage it! I don't think there are any options better than Uppatvind for the HEPA filters at this price point, but charcoal has no clear-cut winner.

For the Nyttig Fil 559 carbon filter add-on, you will need to print 1 lid, 1 base, 2 sides, and 2 Nyttig Fil 559 cartridge halves. Additionally you will need to print a section spacer (as above) if you are adding it to a core section, or two in/out panels for connecting to air ducting hose (as above). There is no window lid option (as there is nothing to see) but different text options are included.

While the Mafuchit Core uses heatset inserts throughout, this add-on also uses standard M3 hex nuts. This is so that screws can be started or ended from within this add-on. This keeps the side panels the same on both sides and allows for maximum with what it is attached to, and how.

Printing instructions

• All parts in all options are oriented for printing. 
• No supports are needed for any model part.
• PETG is the recommended material due to the toughness helping with durability. PLA is more brittle and we don't need its rigidity, ABS/ASA are more prone to warping which may cause air gaps and so leaks.
• Parts are thick-walled to keep Mafuchit tough. This means you can use cheaper material and still get an excellent result. I printed mine with £10/kilo PETG.
• I would highly recommend using an unhardened nozzle for printing, and not going at super-speeds. This should ensure the best quality result as better extrusion adhesion will reduce the likelihood of leaks or part failures.
• Suggested: 0.2mm layer height, 0.4mm nozzle. 4-5 walls, 3-4 top/bottom layers.
• Being multiple parts of 200 grams or less could be a good excuse for using up old unfinished spools of filament, giving you a colourful Mafuchit!

MMU Lid printing instructions

• Make sure you have at least two filament options available in your slicer.
• Required parameter: 0.2mm layer height.
• Load the 3MF file in to your slicer.

• Say “no” if you are asked to convert to millimetres.
• In some slicers you will not be asked if this is one model of multiple bodies. This is because all bodies have the same starting Z height. So, we need to assemble it into one Part ourselves.

• Select all bodies, and Assemble (eg Orca Slicer: select all, right-click, Assemble).

• The letters should all be one filament option in your slicer, and the main body should be the other. If this is not the case, change just the main body (the only body not named “Body1” etc) to your second filament option.
• Slice and print - it should only need 1 filament swap on the first layer. If it is trying to get you to do more, please make sure you have Assembled all bodies into a single Part first. Otherwise you can set the first layer filament sequence to override this.

• If you have not used material switching mid-print before, I would suggest doing some test prints beforehand. You may need to adjust your machine GCode options.

Window printing instructions

• Required parameter: 0.2mm layer height.
• Slice the model as you would normally.

• Add a pause at the start of the layer at 3.2mm. Eg for Orca Slicer, move the layer view slider on the right to 3.2mm, right click on this slider, and click Add Pause.
• Slice the model again, then print.
• If you have not used automatic pauses mid-print before, I would suggest doing some test prints beforehand. You may need to adjust your machine GCode options.

• When the printer pauses, lower the built plate temperature as much as you can without risking the part coming off the bed, and put polypropylene packing tape on the build plate over the area the window will cover. Despite the 1mm air gap, my prototype left acrylic permanently bonded to my build plate in this area. Taping over the build plate provided ample protection. Just don't burn yourself! On my printer I dropped it to 70 degrees which worked fine with the tape.
• Using glue stick on the acrylic window, stick the window into the recess. DO NOT USE SUPER GLUE as at these temperatures it is at best a serious irritant to eyes, nose and mouth. Ask me how I know.
• If the acrylic warps slightly after being put in but before resuming printing, flip it over and see if that is better. The proximity to heat may cause it to warp like other materials do.
• Resume printing, but monitor the print during this first covering layer.. PETG bonds straight to acrylic without issue and will provide a reasonably well sealed window embedded within the part. I have not tested other materials. Your mileage may vary.
• Once the first layer on top of the acrylic window is done you shouldn't need to worry, but please use your own common sense. It's your printer not mine, I am not responsible for it!

Why 0.2mm layer height?

• The MMU text is 0.2mm deep. The cavity for the window starts at 1mm and continues for 2mm.
• All walls are 4mm thick.
• Many printers use lead screws for Z travel, with many of these only able to do 0.04mm resolution. As a result, many printers are unable to achieve 0.25mm layer heights.
• So, the best common layer height that fits the model parameters is 0.2mm.

Assembly

This uses Voron-spec M3 heat-set inserts (info in BOM below) and M3 counter-sunk screws. Glue could be used if desired, but this would stop any flexibility down the line so I wouldn't recommend it. If you are very concerned about keeping Mafuchit air-tight around these seams, I would suggest using a thin bead of bathroom silicone sealant along with screws, instead of adhesive.

Magnets are used for the lids. The spaces for these are slightly wider and shallower than the recesses for the heat-set inserts, and closer to the corners. Don't mix them up! I found the lid can friction-fit reasonably well but am still using magnets for extra reassurance the lid stays in place.

Assembly should be fairly straight-forward - insert all heat-set inserts, screw two side panels to base and the in/out panels on, glue all magnets in (tip: have one big line of magnets, and put in magnets from one end into the main body, and from the other end into the lid). Enjoy the clean air!

If you need a reference, I have included a STEP model of the same assembly configuration as in my video.

For the carbon filter add-on, this uses hex nuts in some areas. The space for these will stop them from turning, but may be a little fiddly getting the screw to engage with the thread to start with. If you are not using a hex nut here, the space should be sufficient for an M3 screw head of nearly any type.

If you are attaching two or more sections to each other (eg Mafuchit Core plus carbon filter add-on), you will need the Section Spacer model as well as longer screws. The longer screws go through the Section Spacer to the other section, rather than screwing directly into it.

I would suggest screwing on the side panels of the add-on to the Core first, then the base. I think that should make things less fiddly.

For the in/out panels with 120mm or 140mm fan mounting spaces, these also use Voron-spec M3 heat-set inserts. Technically PC fans are sized for M4 screws but M3 screws should work fine with a washer if necessary.

Bill of Materials