Filament Spool Desiccant Canister

A desiccant canister designed to be mounted in the center of a spool of filament during storage to help keep the filament dry. The canister has a lock-ring which threads onto the opposite end from the cap, after the canister has been inserted into the center of a spool of filament, which secures it in place and prevents the canister from falling out.

The cap and lock-ring have been designed to be low-profile so the spool will still fit inside the original packaging bag and/or box with the desiccant canister in the center.

There are two version of the cap; a standard cap and one that accommodates one of the common round hygrometers (thanks to zijiewang178 for the suggestion!).

Inspiration for this design was taken from the containers designed by gdrag and Malolo. The lock-ring design was inspired by Repkord's RepWinder.

Print Recommendations:

• PETG or another material with higher temperature resistance (so you don't have to worry about removing the canister when you put your spools in a filament dryer).

• Use a 0.4mm nozzle* at 0.2mm layer height.
  *I no longer recommend using a 0.6mm nozzle because what you gain in reduced print time, you lose in print quality. Through additional testing over time, I've determined the resultant print quality is much better and requires less post-processing (if any) when printed with a 0.4mm nozzle as opposed to a 0.6mm nozzle. With input shaping, the print time difference between the two is negligible; about 40 minutes per complete canister (not including the funnel).

• It's recommended to use a height range modifier on each threaded part to drop the layer height down to 0.1mm for the threaded areas. While not required, it does improve the finish quality of the threads.

  • Height ranges are as follows:

    • Canister = 0-10mm & 59-70mm.

    • Prusament NFC Canister = 0-10mm & 55.6-66mm.

    • Cap = 2-12mm.

    • Lock-ring = 2-10mm.

    • Funnel = 24.8-35mm.

  • For other parts not listed above, start the height range modifier at the base of the threads and end it at the top; only the threaded portion should be subject to the H-R modifier.

• Print the funnel upside down — threads facing up.

• 2 perimeters.

Assembly & Use:

• The cap and lock-ring have opposing threads, so you can't mix them up and accidentally spill all of your desiccant everywhere.

• Use the funnel for filling; fill to about 2-3mm below the top of the funnel neck.

• When screwing on the cap, you may need to jiggle the canister a little as it threads into place to coax the desiccant beads out of the thread path.

• The underside of the flange on the cap should be flush with the top of the canister. If you can't get the cap to screw on all the way with a little jiggle-jiggle, then the canister may be over-filled; pour a little out and try again. Once you are able to get the underside of the cap flange flush with the top of the canister, give the cap a little extra snugging (a bit more oomph on tightening it, but not too much!); this will prevent the cap from being inadvertently unscrewed when manipulating the lock-ring.

• Insert the filled canister in the center of a spool of filament and secure it by threading the lock-ring on from the opposite side. The lock-ring does not need to be cranked down in order to secure the canister in the spool! Doing so could cause you to inadvertently unscrew the cap when trying to remove the lock-ring and subsequently spill desiccant everywhere! The lock-ring only needs to be gently secured against the side of the spool to perform its intended job; no uggah-buggah necessary!

Hygrometer Cap:

• For the hygrometer to fit correctly in the cap, you will need to slightly bend the lock tabs out away from the body of the hygrometer — be careful not to bend them too far, or they will break; ask me how I know.

• Once the hygrometer is inserted into the cap, you may find it necessary to use a small flat-head screwdriver to again bend the tab outward to get it to engage on the underside of the cap, holding the hygrometer in place.

• Fill the canister with an appropriate amount of desiccant, allowing enough room for the hygrometer when the cap is fully seated.

• Available on both the standard cap and the adapter cap for Sunlu spools.

Notes:

• 2 canisters with caps and lock-rings (no funnel) will fit on the MINI/+ print bed.

• 3 canisters with caps and lock-rings (no funnel) will fit on the MK3/S/S+, MK4/S, or CORE One/+ print bed.

• ?? canisters with caps and lock-rings (no funnel) will fit on the CORE One L print bed. I don't know because I don't have one and that makes me sad.

• ?? canisters with caps and lock-rings (no funnel) will fit on the XL print bed. I don't know because I still don't have one and that still makes me sad.

Change Log:

• 30AUG2022: Minor description adjustments; added 3 additional photos.

• 13SEP2022: Added shorter (58mm) canister and adapter cap & lock-ring for Sunlu spools (72mm ID).

• 05FEB2023: Added thick-walled funnel.

• 26MAR2023: Added hygrometer cap.

• 29AUG2023: Added canister extension ring to convert Sunlu (58mm) canister to standard height.

• 23DEC2023: Added adapter cap with hygrometer cutout for Sunlu spools (72mm ID); thanks to Reika for the suggestion! Added remix “differences” description. Updated some text in the description. Corrections to file naming.

• 15JUL2024: Updated canister model file with increased clearance on the threads to reduce friction in these areas and limit or eliminate the need for any post-processing or break-in; thanks to TheSpyWhoLovedToBake for sparking the idea to revisit and improve this area of the model. Updated description to remove 0.6mm nozzle recommendation (with explanation). Updated G-code files. Updated cover photo.

• 19JUL2025: Updated nearly all of the model files with improved thread geometries and clearances; unified latest design updates across all parts. Revised print files.

• 20JUL2025: Added adapters for generation 2 and generation 3 Sunlu spools; added canister for Protopasta 500g spools (61mm), which will also work for generation 1 Sunlu spools; updated and/or corrected some file labels and reorganized file folders. Special thanks to Dave_Rowland for bringing the different generations of Sunlu filament spools to my attention.

• 25JUN2026: Updated description text to mitigate a potential issue where the canister cap could be inadvertently unscrewed when trying to remove an over-tightened lock-ring. Thanks to Richard Zimmerman for prompting me to add these additional use instructions.

• 11JUL2026: Updated description text. Updated nearly all models with the latest version, which includes a modification made to the canisters that should prevent desiccant from jamming the cap when threading it on all the way until tight. Added a new canister and adapter lock-ring for Prusament NFC spools. Updated print files.