This is my take on the beautiful and useful Spannerhands spool system.

Parts are collected from various things, modified by myself or newly created.

Two new features are:

• detachable gelbox (no need to pour gel beads into or out of the cassette)
• filament guide inside the PTFE coupler (filament doesn't get stuck when inserted)

Apart from printed parts you'll need:

2 x 608 bearings (id 8 mm od 22 mm)
12 x 10 mm M3 screws + nuts (locknuts adviseable)
1 x fitting for PTFE tube (with R1/8 male thread)
1 x PTFE tube
1 x 4.7cm x 2.7cm x 1.3cm hygrometer

No supports are needed unless suggested explicitly.

Print the following in PLA. I usually use 0.15 mm layer height in order to get the gutter for the flex seal smooth. In order to get the box reasonably air/moisture tight, I used 3 perimeters, 8 top and 6 bottom layers (for 0.15 mm).

1 x base (print with 10 mm brim!)
1 x lid (10 mm brim)
1 x hinge (can be printed horizontally without supports)
1 x hinge nut
2 x 608 bearing mount
1 x core

If you need a wall mount, you can choose between a mount screwed directly to the wall:

1 x wall mount

or a mount attached with sliding nuts to a 20 x 20 T-slot profile:

1 x 20x20 T slot mount

For some reason, I printed the following in orange PETG (again, think about thickness of perimeters and top + bottom):

1 x ptfe coupler
2 x clasp bracket

The seal should be printed in some very flexible material (92 ShA or less) and <= 10% infill:

1 x flex seal

The clasp, on the other hand, should be printed in a material with 98 ShA and 80% infill:

1 x semi flex clasp

Finally, I've modified the base to have a replaceable silica gel container which you need to print in PETG to withstand drying in a fruit and mushroom dryer without deformation. I would recommend to print it in clear PETG if you use silica gel with an indicator color such that you more easily can see the state of your gel. The gel box should be printed with the perforated side oriented downwards:

1 x gelbox2 (change orientation and use supports!)
1 x gelbox2-lid

As an alternative to the core, you could consider using an auto-rewinding core.