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Airtight Filament Canister

by henryarnold Feb 11, 2016
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I think the clear Zylar 21 cup cereal box supply has run out in the US. I can't find one for a decent price. Has anyone had luck with another brand?

What did you use to stick the clip to the side of the box?

3M Double Sided Tape. The type with foam between adhesive.

Looking at the images, there seems to be two systems - one where the filament comes out of the top, and the other through the base. Which is the recommended?

It's your choice and depends on where you want to place the container. if you place the container on a shelf above the printer, feeding from the bottom will work best. If you place the container on a table or lower than the printer, feeding from the top is best.

I guess the 3D market has driven the price of these Rubbermaid canisters up. They are sold out most places and the cheapest price on Amazon is $22 (for the better quality Zylar version). What's crazy is it's cheaper to buy this 6 piece set which contains a single 21 cup than it is to buy only the 21 cup: https://www.amazon.com/Rubbermaid-Modular-Storage-Canister-1840750/dp/B078Z7JV7T/

What size are the bearings for the adjustable spool roller?

Great design! I will use it for all my filaments that I am printing with.
Can you please explain where you are using the filament guide and how to install it?
I have Hypercube printer. Maybe a picture or 2 would show me how to mount it.
Thanks again for your hard work.

The HyperCube doesn't need a filament guide. The guide design is for the Prusa i3 with the filament feeding from overhead such as a top mounted spool or a shelf above the printer.

I added a photo showing the guide on a HicTop Prusa i3

Did you just use a lock nut for the back side for the fitting? Also, did you have better luck with having the outlet on the lid like in the post processing section or at the bottom of the container like on the pictures?

No nut is needed. The fitting self threads into the hole. Teflon plumber's tape makes sure it seals.

CONTAINER : Rubbermaid
Stores that carry this : WAL-MART (YES YOU ALL ARE CLOSE TO ONE)
Price : $13.47CDN (Thats like $3US)

Canada Link : https://www.walmart.ca/en/ip/rubbermaid-16-cup38l-premium-dry-food-storage-canister/6000195704138
(Its this one but the 5L/21Cup size. This one is just a tad smaller.

American Link : https://www.walmart.com/ip/Rubbermaid-Saves-Space-In-Your-Pantry-1-0-CT/38664652

I'll probably just end up trying to do it on my own, but have you thought about connecting the bearings of the spool holder with cylinders so you don't actually need to adjust it?

Good idea! Can you do a remix to add your improvement?

Well, I tried this just now and am using the RM dry box for the first time. No bueno. There is too much drag on the filament, and the dry box is periodically being pulled toward the printer (Anycubic i3 Mega), sometimes even lifting up.

Some things that I have done differently, which may be causing the problems.

  1. I am using the riser tray referenced above.
  2. While I am using the same pneumatic coupler as in the images above, I have placed it about 30 mm higher to account for the added height caused by the riser and to make the egress just about even with the level where filament comes off the bottom of a full spool, but I now see that perhaps 15 mm lower would have been better, especially for extruders that feed from the bottom. I was trying to decide what would be best for a wide range of printers.
  3. I am using only about a 6-cm section of 4mm/2mm regular PTFE tubing for the egress.
  4. I am using the Tush++ roller assembly, which may create more drag on the spool, due to calipers-like rims around the bearings. I should try HenryArnold's adjustable roller.
  5. Perhaps due to the smooth surface of the riser, the filament spool touches the front wall of the RM container as it spins, certainly creating more drag. Is it imperative that the filament spool not touch any part of the RM container as it rotates?

What about using PTFE that has an internal diameter of 3mm and an outside diameter of 5mm or 6mm to reduce friction along the feed path? Is there a pneumatic coupler available for such size tubing?

I found some OD4mm/ID3mm PTFE tubing that I will try.

I've been using 4mm/2mm for a long time with no drag. I can't explain why you are having problems.


Do the front of your spools spin against the front of the inside of the RM container, or do you somehow keep the spool centered inside the container?

I add stick on rubber feet from Home Depot to the bottom of the spool holder so that the spool stays centered and does not touch the container. My spools turning freely and there is no binding on the tubing.

One interesting problem I have notice is on a spool that has been in the container for a long time unused, the section of filament that is inside the PTFE tubing can sometimes become brittle and break. This could be a sign of moisture except that the rest of the spool is fine. When this happens, I just rethread the spool and seal the container.


I have also been experiencing filament in the 2mm ID PTFE tubing (on a spool that has sat unused for several days) becoming stuck just enough inside the tube that filament breaks somewhere along that path. Maybe this is due to different moisture levels inside the RM container with desiccant beads and moisture levels inside the PTFE tube outside the RM container. This is in a printing room that has a constant humidity of about 59%. If I can just find where I put it, I want to see if OD4mm/ID3mm PTFE tubing solves this problem. The only drawback to this is that more moisture will enter the RM container with the larger ID PTFE tubing.

I have found my id3mm/od4mm pfte tubing and will now put it to work. If I experience no breaking of filament within a two-week period, I will know that this is a critical point.

I think the moisture gets in through the cap allowing the filament to become brittle but only inside the tube. Try a small amount of silicone rubber inside the cap to create an airtight seal.

I've had this happen also but only after the spool has been in the container for weeks. When it does happen, only the section inside the tubing becomes brittle. I cut it off and rethread the tube. The spool is fine. I think the solution is to seal the cap by putting a dab of silicone rubber inside the cap. With the silicone rubber the cab will be airtight. Try it and let me know if it helps.

I'm not printing constantly, and I just leave the spool of filament threaded in the printer. Prior to using the Rubbermaid dryboxes (filament spools open to the elements), I was not experiencing breaking of filament between the extruder and the filament spool during periods of non-use. This problem started occurring only with the use of the dryboxes with 4mm/2mm PTFE.

That said, I think the OD4mm/ID3mm PTFE has solved the problem, though it may be a bit too soon to tell. The only downside is more moisture is likely allowed in through the small gap in the PTFE between the inner wall of PTFE and the filament, which means that the desiccant beads inside the drybox will have a much shorter cycle.

I can think of two ideas to mitigate this problem:

  1. Don't leave filament from the spool threaded in the printer during non-use. Instead, snip filament at the extruder, push filament back inside the 4mm/3mm PTFE, and cap PTFE as Henry suggests. For the next print job, feed filament into the extruder, butting it up against the snipped piece of filament already in the Bowden PTFE from the previous print job. The newly threaded filament will push the old filament out during printing.

  2. Leave the filament threaded in the printer, but find a way to seal the opening of the 4mm/3mm PTFE around the filament, perhaps wrapping it with plumber's tape or something similar.

I always remove the filament from the printer, push it inside the canister tube and cap it. Even then the last 6 inches can become brittle. I think the solution to that is to add silicone inside the cap to seal the end of the tube. Leaving the canister on the machine allows air to leak into the end of the tubing. Short term this is OK but long term it will allow air into the canister.

Say no more. I will secure the cradle, both yours and the Tush++, so that the spool does not touch any part of the inside of the container.

I think I'll use squares of double-sided foam tape on the middle pad of each side of the cradle.

Thanks for the response. It is helpful to know that someone is using 4mm/2mm successfully. The Tush++ roller assembly works fine outside the Rubbermaid container, but inside the RM contain gradually is pulled to the printer, the front tip even being pulled off the table about a centimeter.

Henry, today I printed your adjustable roller assembly for the first time. Maybe this will work better than the Tush++.

I did not design the Tush++ cradle. It's possible that it doesn't work with the Rubbermaid container. My 3 piece cradle works fine. One tip is that some bearings have heavy grease inside keeping them from turning freely. I wash the grease out with WD-40 and then add a light oil like 3 in 1 Oil. As far as the 4mm/2mm tubing, everyone uses that tubing in their Bowden setups and I don't hear of any problems. Is it possible you received some bad tubing?

I'm glad you mentioned that about the bearings. I use grease-less and caseless spinner bearings not designed for skateboards that spin very freely and have been experimenting with them. I'm happy that you confirm the need for bearings that spin more freely than the norm. I'm using only a 6cm section of tubing for the filament egress. It's not a scientific test, but I manually compared sliding filament through the regular Chinese 4mm/2mm PTFE that I'm using and Capricorn PTFE, and I could not decipher a difference in friction. Perhaps, I should try actually printing with the Capricorn PTFE in place. My order of 4mm/3mm PTFE should arrive from China in three weeks.

I have to recommend this riser tray to anyone making this. It separates your desiccant from your rollers. It fits perfectly in the 21cup containers. I've already made 2. https://www.thingiverse.com/thing:2562434

Internal Riser Tray for Filament Housing
by JinrenC

Very nice. I frequently use Nylon filament ... and Nylon loves humidity ... (unfortunately).

One other addition, might be to add a container for desiccant inside.
(You can get a bottle of re-usable desiccant granules from Amazon.)

Maybe a smaller version of: https://www.thingiverse.com/thing:2180264 ?
But some way to suspend it out of the way of the spool.

Helps to keep things inside nice and dry

Cylindrical Desiccant Box
by Dralion

Do you use this for your nylon filament? Is it working?

I'm looking for something like this to store my nylon, too.

This canister works for any filament. Add desiccant to assure a dry interior.

There is plenty of room on the inside of the lid. A rectangular desiccant container would fit.
I just throw the packets on the bottom.

Yeah, that's probably the right answer for me ... I'll come up with some sort of container that mounts to the lid and suspends the desiccant granules both fore and aft of the spool ... Good idea, thanks.

I like this design a lot...However, it appears my enclosure is just a little too short to accommodate this container vertically...Do you know of a way that would allow this to dispense the filament with the container placed with the cap facing forward, instead of up. Of course attaching the nozzle and tube would be no problem, Im just trying to think of a way for the spool to be able to spin freely.... Any suggestions?

Unfortunately the cradle only works in the bottom of this container. You may be able to find a different container that is shorter.

Ok noob question... The port you designed on top of the unit is obviously larger. Is that for a different size filament or what? Why not use the same size on the top or side?

The larger port was my original design which uses 0.250" PTFE which is available from Home Depot. Later I decided to switch to 4mm/2mm OD/ID PTFE which most people will have to order online. For the 4MM PTFE I use the standard connector. You may use either design and either design may be mounted on top or on the side.

The pins that hold the bearings in is really hard to put in, am I doing something wrong?

You guys are right. I made the pins and the holes 8 mm which is too tight. I opened up the cradle holes to 8.3 mm and published both cradles as V3. Thanks for catching this.

I also found the pins way too tight so in Cura I changed the x and y size from 1.0 to 0.9 and they fit perfectly! I always hate sanding something that small lol.

Sand the pins and if needed drill the hole out. On my printer I only have to sand the pins.

Do you have a link for the "10mm PTFE connector" on amazon.com?


They are good quality. I have added these ports to all my canisters with the other style port.

I assume you used a 10MM nut on the inside. Did you need to use a rubber washer to keep it air tight?

No, I did not use a nut. I drilled a 13/32" hole and used two layers of Teflon tape to seal the connection. The fitting self threads into the soft plastic. You could probably leave off the Teflon tape and it would also seal fine.

I've ordered 10mm nuts with a 1mm pitch to use with the couplers, but I'm not sure if the thread pitch on the couplers is .7mm or 1mm.

I added a new filament port design that supports 4/2 mm diameter PTFE tubing and can be easily mounted low on the canister for support of printers with an extruder that receives filament from underneath.

Any chance of getting the CAD files for this? I've printed them but the fit for 1/4" is too tight, needs a bit more tolerance.


Have anyone try the TILLSLUTA ?

The OXO container is not suitable as the hand grap get in the way.

I keep looking for an airtight rectangle container

I did a search on "Cereal Storage Containers". You are right. Many of them have undesirable lids or are too small. This one looks like it might work. Its the right size and the top has only a small cap.


Any specs on the bearings? Looking to order them online.

Nothing special. They are just 608 bearings commonly used for skate boards. Lots of designs use them and they are available from hundreds of sources. The cheap ones work fine for this cradle. Here's where I bought my last set:

Thank henryarnold.

This is why I was puzzled. Went to Amazon UK. Look for the container with the same name & model number. But, it cost 10 times more expensive. Is this due to import tax, VAT etc?

Try a different brand. The size needs to be around 26cm x 11cm x 25cm or a little bigger. This container can be found by doing the search "Airtight Cereal Container". I found multiple containers that will work on the Amazon UK site. Here's one with great reviews:


The OXO may be even better quality than the Rubbermaid I use and its the same price taking into account the British Pound/USAD exchange rate. Good Luck. Be sure to post photos especially if you use a different container.


In UK the container is selling for over £50 any suggestion for cheaper one in the UK?

Yes, I went to www.ebay.com.uk and found quite a few airtight containers that would work. Do a search for "Airtight Cereal container" to find one. Read the reviews to make sure no one complained about the product not being airtight. Do you have Amazon.com in the UK? If you do, you might do the same search there.

Excellent design. Love it! When blowing thru the tube you can see how pressurized this design is.