A Comprehensive Guide to Keeping Your Filament Dry

Summary

This is a practical guide on how to keep your 3D printing filament dry with as little effort, cost, and power consumption as possible. I will compare different drying and storage methods and explain what actually works long-term.

My final design can be seen here:

Tools & Materials

For one filament Drybox:

1. Print Filament Drybox - All in One - PETG
   

   
   

2. Print Filament Drybox - All in One - TPU
   

   

3. Buy 1 m M8 threaded Rod
   Gewindestange 1 m DIN 976 M8 galv. verzinkt 1 Stück | HORNBACH AT
   

   

4. Buy 16x 608RS Bearing
   50 Stück Kugellager 608RS Skateboard-Kugellager 9 x 22 x 6mm Double Shielded Miniatur Rillenkugellager Carbonstahl Präzisionslager 608 Kugellager für Skateboards, Rollerblades, Fahrräder, Hausgeräte : Amazon.de: Sport & Freizeit
   

   

5. Buy 3 mm ID × 4 mm OD PTFE Tube
   ALLY-MAGIC PTFE Schlauch 4 Meter 3D Drucker PTFE Tube Teflonschlauch Zubehör 3 mm ID × 4 mm OD für 3D-Drucker Extruder E22-TMSFG4M : Amazon.de: Gewerbe, Industrie & Wissenschaft
   

   

6. Buy IKEA Samla 22L incl. Lid
   SAMLA box with lid, transparent, 39x28x28 cm/22 l - IKEA Austria
   

   

7. Buy Liquid silicone rubber
   LET'S RESIN Flüssiges Silikon Kautschuk, 580g Lichtdurchlässiger Abformsilikon, 1: 1 Verhältnis Mischungsverhältnis Silikon für Silikonformen, Harzformen, Kerzenformen: Amazon.de: Baumarkt
   

   

8. Buy Silica desiccant
   Silica Gel Trockenmittel 2kg – Luftentfeuchter mit Farbwechsel-Indikator & regenerierbar – Wiederverwendbarer Entfeuchter für Schuhe, Kameras, 3D-Druck Filament, Elektronik & Aufbewahrung : Amazon.de: Küche, Haushalt & Wohnen
   

   

9. Buy aluminum mesh
   vidaXL Aluminium-Geweberolle 100x500 cm, Silber, Feines Insektenschutznetz für Fenster und Türen, Langlebiges Metall-Fliegengitter, Schädlingsschutz für Haus und Garten : Amazon.de: Baumarkt
   

   

Equipment: Drill, stapler, side cutter, mask.

Print Instructions

Support is necessary only here.

Brim on part Metal Rod Holder might be needed.

Assembly

1. Remove support

2. Cut PTFE tube to desired length (at least 15 cm long)

3. Put PTFE tube into flange

4. Widen PTFE Tube ends

5. Fill flange with silicone starting from inside the thread (use a mask ⚠)
   See pictures - marked in orange 🟧
   

   
   
   

6. Fill IKEA Samla rim with silicone
   

   
   

7. Cure for 24 h at room temperature in a well ventilated room

8. Remove outside rim of part flange with side cutter
   

   

9. Cut 4 oval holes 23 mm x 15 mm into IKEA Samla box by drilling small holes and using a side cutter
   

   

10. Put Outlet part in holes

11. Add Press part

12. Add Screw cap part
    

13. Cut M8 rod into 33 cm pieces
    

14. Put a bearing between 2 discs

15. Put bearing with the discs into bearing holder

16. Put bearing holder onto the rods

17. Put assembled rods into IKEA Samla box using Metal Rod Holders
    

18. Add silica inside a container with max 4 cm in height (e.g. aluminum mesh bags) to the bottom of the IKEA Samla box

19. Add filament rolls

20. Adjust bearings positions

21. Close lid

22. Place another box or something heavy on top

23. Insert PTFE Plugs

Done 🥳

For more details see chapters below!

Testing Process & Findings

Possible Solutions ➡ Storage box with silica

1. Food Dehydrator 
   

   

   
   Most food dehydrator do not actively drain the removed water. They can be quite expensive if larger. You cannot print directly out of them. They cannot be used for storage.
    

2. Keep a low humidity within the room
   

   

   
   Not ideal for living in it. Most dehumidifier can only achieve a minimum of 30 - 40 % RH.
    

3. Keep filament within 3D printer enclosure
   

   

   
   This works for about 6 - 24 h if the door is kept close, so it cannot be used for long therm storage.
    

4. Not printing with water absorbing filaments at all
   

   

   
   Not acceptable. Pretty much limits to only using PLA.
    

5. IR lamp for drying filaments
   

   

   
   Only heats up surface.
    

6. Inline filament dryer
   As seen in Inline 3D Printing Filament Dryer | Does It Work? - YouTube
   

   

   
   Probably does not work. Probably high power consumption.
    

7. Filament Storage box with connected dehumidifier
   

   

   
   Again hard to find models which can achieve sub 30 % RH that are not industrial.
    

8. Filament Dryer or DIY Filament Dryer with heating Elements
   

   

   
   Expensive when used for storage and for more than 4 Spools since multiple units need to be acquired. Can be used in combination with other filament storage method to dry filament that's already wet. Also most models do not feature a way for the hot air to escape so you are better of using an old oven for example.
    

9. Solid State Dehumidifier
   

   

   
   Solid-State Dehumidifier: The Ultimate Filament Dry Box - YouTube
   Technically the most maintenance free option, but with around 150 € for a 22L box it is really expensive.
    

10. Vacuum Pump
    

    

    
    Vacuum VS Dehydrator! What's the best way to dry filament? - YouTube
    Dries less effective than an oven. Cannot be used to directly print out of it.
     

11. Filament Storage box with desiccant
    

    

    
    Silica or activated alumina or zeolites are cheap an can mostly be reused. They last for a long time of about 3 - 6 months if properly sealed. We can work on that. The changing of filament is quite tiresome and can be even dangerous if breathed in, but we can work an that too.

In the end I decided that a storage box with silica would be the best solution to move forward.

Finding the right storage box ➡ IKEA Samla box 22L

When searching for a good storage box I tried to search for boxes which seal very well and fit multiple spools of filament without being too big or too heavy to carry when filled with spools. I compared multiple local or used boxes, but decided to stick with the fan favorite IKEA Samla box 22L. They are cheap, available around the globe and are probably not discontinued within the next few years. Bigger IKEA Samla boxes left much of the inside space unused when filled with spools. 

Also, if you prefer each spool in a single box I can recommend: The Ultimate Cereal Container Filament Drybox by GunplaMark | Download free STL model | Printables.com
 

Spool Holder ➡ Modified Version of Filament Drybox by SkyBeam

Spool holders basically fall in one of two categories, ones which hold the spool up through the middle and the ones who hold the spool up by its outer edge.

In the past I had problems with high and inconsistent drag on the spool during printing when using the pole through the middle method. E.g. the Prusa Spool with its dent on the inner edge. This method also has the disadvantage that it does not allow easy filament changes of a single spool if it is placed beside other spools. Another disadvantage is that, without spacers between the spools they sometimes unwind the spools beside them.

Deciding on the second outer edge method, I tried just two PVC pipes to hold them up but they were causing too much drag. So I needed bearings. I tried 3D printing them as well but non came close to the ones which are commercially available. If you absolutely have to print them I recommend these ones: 608 ball bearing by filou3D - Thingiverse. I also tried PTFE tubes as gliders as seen in this Model: Let＇s build…Drybox v2! by Ren | Download free STL model | Printables.com. They caused less drag than the PVC pipe but more than a bought bearing. Additionally, they started to deteriorate after a few hours of use.

608rs bearing is what I used. I removed the outside protection. Cleaned them with IPA and reapplied some WD40. Be careful not the buy the 608zz bearings. They cannot be cleaned from the inside.

For the holder itself I modified the design by Filament Drybox Ikea Samla 22l remix by SkyBeam | Download free STL model | Printables.com.

The bearing holders designed by SkyBeam did not need extra nuts to keep them from moving once the weight of the spool is applied. I simple put on the spool, adjust their position and they stay without moving left or right during printing.

For the rod I used M8 threaded rods. No need to buy expensive stainless steel here since it should be always dry in our boxes. I bought 1 meter and cut them into 33 cm pieces. So 2x 2m rod are enough for 3 boxes. No waste here. 

Keeping the spools high up inside the IKEA Samla box gives extra width, because of it's tapered design. It should fit 4 normal spools (69 mm width) or 4 Prusa spools (75 mm width) or 3 Amazon Basics spools (77 mm width and 1 normal spool.

Airtight Seal ➡ Self cast silicone seal

As you might know the IKEA Samla Box does not come with a rubber seal. This is crucial because it means the silica might need replacement every few weeks without it.

I tried:

• Double D Profile EPDM seal

• Flat EPDM seal

• Silicone seal used in car doors

• TPU Printed seal
  
  "Packning": Gasket for IKEA Samla 22L - Free 3D Print Model - MakerWorld

• Self cast rubber seal
  LET'S RESIN Flüssiges Silikon Kautschuk, 580g Lichtdurchlässiger Abformsilikon, 1: 1 Verhältnis Mischungsverhältnis Silikon für Silikonformen, Harzformen, Kerzenformen: Amazon.de: Baumarkt
  

  

I Used the same amount of silica in each box and a humidity sensor. 

The 3D printed seal performed by far the worst. All commercially available seals performed about the same. The self poured seal outperformed every other seal by far. This is also visible by pressing down on the lid and seeing the sides bulge outwards. Please use this method, it is fast and easy. Just mix 1+1 silicone together pour it in the outside rim. Make sure it is laying on a flat surface. Be careful not to overfill it. Just a thin layer around the brim is enough. Let it sit for 24 h at room temperature. Done.

Clamps? There are dozens of clamp designs for the IKEA Samla box, I tried a view of them but decided on just putting some weight on the boxes or another box. It is cheaper, causes a more even pressure distribution compared to clamps and it is often way faster to open and close the boxes. Additionally, you do not have to worry about the clamps deforming over time. So please do not print these if not necessary. 

Outlet  ➡ Custom 3D Printed Design

My goal for this was to be able to feed the filament upwards or downwards from the drying box. It also had to be as airtight as possible and it should also introduce the least friction possible.

I tried a modified version of this Filament passthrough for storage box by emilbp | Download free STL model | Printables.com. I used silicone adhesive to glue it to the box, but the PTFE Tube kept getting loose over time. Additionally, changing the direction from down to up would take some time.

That is why I came up with this design. It is meant to be filled with silicone to create an airtight seal around the filament outlet and it also helps to hold the PTFE tube in place.

The screw cap holds the PTFE Tube in Place. The Part in blue is meant to be filled with silicone (orange) like this: 

After printing of all the parts, cut a piece of PTFE Tube to your preferred length. Insert the PTFE Tube into the designated hole. Put the part on something to keep it level. Use a cup with a spout or a syringe to fill the inside of the outlet with liquid silicone. Once it reaches the overflow you can use the remaining silicon to fill the outside pool. After 24 hours of curing at room temperature remove the outside rim with a side cutter, so it looks like this.

Now its ready to be inserted into the box. To cut the holes you can use this stencil. The oval holes need to be around 15 mm in width and 23 mm in height. I used a drill to drill small holes around the perimeter of the desired holes and then used a side cutter to connect the drilled holes.

Position wise, to enjoy low friction on empty and full spools I recommend these for my outlet. They do not have to be that precise.

Now, if you ever want to change the orientation from down to up or vice verse just unscrew the cap. Turn it 180° and screw the cap back on.

Preferably use 4 mm Outer Diameter & 3 mm Inner Diameter PTFE Tube for less friction. Slimmer PTFE tube should only be used after the extruder for better retraction.

Silica container ➡Silica within aluminum mesh

Initially I was planing to hang boxes of silica on the lid to make it heavy enough to seal the box by it's weight and to swap it easily for regeneration and a possible increase in drying performance but this idea was scraped due to complexity of glue or screwing something onto the lid. Plus it has the benefit of being able to fit wider spool into the box.

Pouring in loose silica beads into the box and collecting them for regeneration is a messy and potentially dangerous process due to the risk of breathing in small airborne glass particles. Silica can be regenerated at around 120 °C but it works best at around 160 - 180 °C. Next to none 3d printing materials can survive that. So i started looking into metal mesh containers but did not find any which would both fit and have a narrow enough mesh.

I used aluminum mesh to make silica pouches. They are held together using a stapler. Stainless steel meshes work as well but are far harder to bend. 

They take some time to produce but I like how they make handling silica that much easier. For the large ones seen in the picture above I used a sheet of 35 x 30 cm large aluminum mesh filled with around 800 mL of silica each.

If you are not fond of this idea, the box is designed to allow any tray which fits inside the box with a maximum height of around 4 cm  to be used. E.g. Old plates, metal sieves,… (anything metal, glass or ceramic)

As a small side-quest I tried using a microwave for regenerating silica like in this video. Don’t use desiccant bags unless you do this! - YouTube My resume is, that your should not try it. It only works with very small amounts of silica. Trying to regenerate bigger sizes will lead to hotspots. Even shaking the silica around a few times did not resolve this issue for me. The hotspot will turn the silica black and destroy its functionality.

Filament Plug ➡ Custom 3D Printed Design

To keep moist air from entering through the PTFE Tube during storage I designed this plug. It is pressed between the filament and the inside of the PTFE Tube. This has the benefit of not having to rewind the filament for storage. 

I Printed this in TPU95A. I also used a smaller nozzle with a 0.25 mm diameter orifice, to get it printed without issues. I used a knife to open the gap after printing. I used this tool (Reaming Knife) to widen the end of my PTFE Tubes a bit to make it easier for the plug to be inserted. 

Cost per Box ➡ 30 €

• 3D Printed Parts: 3,80 € (20 € / 1 kg)

• Aluminum Mesh: 1,00 € (4,48 € / m²)

• Silica: 10,00 € (56 € / 5 kg)

• Silicone mold: 4,00 € (25€ / 580 g)

• PTFE Tube: 1,00 € (7 € / 4 m)

• IKEA Samla 22L + Lid: 5,50 €

• M8 threaded Rod: 1,00 € (1,25€  / 1 m)

• Bearings 3,20 € (10 € / 50 pcs)

The cost for 1 Drying box is around 30 € (2026-01-04)

Thank you for trying me design and feel free to remix as you please 👍