Summary

Due to request i've uploaded the CAD file of my 8 roll spool holder. This box is moisture-proof, features 2 vertically hinged doors, PTFE guides and a vent for internal dehydrators. There's enough space to fit as much silica as you want if you make a custom box for it. Notice that I made this with spare materials i had around and I haven't designed it with the care needed for a public project, but it gathered attention so I decided to publish it as it may be useful for someone. As such there are surely errors and things that can be improved upon (like the useless square cutouts on the corners of the doors' panels) and i welcome you to remix this design to make it better.

Note on dehydrators: since filament dehidrators are either expensive or don't reach the intended temperatures, i've bought a food dehidrator and made a custom box housing for its electronics in order to circulate hot air inside the box. I won't share the file because it's specific to my dehydrator's electronics so not of much use. During storage the vent stays closed and during drying it stays open as to let out moisture yet keep hot air inside. I suggest you don't include the vent if you aren't planning to add a dehydrator.

BOM:

• 2020 extrusions: (4x480mm),(6x420mm),(4x210mm)
• acrylic panels: please check the cad for sizing. i've used 2mm panels to keep it cheap, but
  i suggest at least 3mm for stability.
• 5 to 8 meters of PTFE tubing.
• 4 Amplifier feet, the ones used on a Voron.
• 36 M5x25 bolts, Flat or philips head
• 4 M5x25 bolts, Hex head
• 8 M5 nuts
• ~100 M3x8 hex bolts and M3 T-nuts
• 16 3x6mm magnets.
• around 10 meters of 5mm x 1mm single-sided foam tape
• 32 625zz bearings.
• 4 2020 90° angle brackets (for the central beams, not depicted in CAD because i used a different solution)

For the optional vent:

• 2x m3 x4x5 heat inserts
• 2x m3x8 hex bolts (included in the 100 sum)
• 3x 3x6 magnets
• some double sided tape
• some foam tape as above to seal for moisture

i hope i didn't forget anything.
I suggest you print the parts in ABS or ASA if you plan to insert a dehydrator.