The parts for this dry box I used the few printed parts and:
-Ikea 792.767.60 dry box
-4mm push-fit connectors (you can use cable glands)
-PTFE tubes 4x1mm
-4x M3 screws, washers and nuts
You need two screw two axis holder across your box - you only need holes for the 3mm screws. My box fits two spools and I attached two connectors for each - one to get the filament out and additional one to stick the free end when not in use, sealing the box.
The deviders are optional - to keep the spooles in place.
The plug could be replaced by any cylinder with ca. 4mm diameter.