This is a Filament Dry Box for a single Spool, based on the Tool Box Parametric model.
To print directly from the box, it provides a horizontal as well as a vertical filament outlet.
The filament outlet nut comes with a M6 thread to mount a PC4-M6 tube coupler.

As a spool holder I used the Anycubic Vyper Filament Spool Holder with Bearings but the standard spool holder from the Anycubic Vyper will fit perfectly too.

I also added a Tool Box Seal that can be printed in TPU to make the box more airtight.

You can add up to three desiccant boxes to adjust for your humidity levels. Just print the dessicant boxes, the box clips and one funnel.  After filling the boxes close them with the clip and slide them into the rails.