Combine with a IKEA samla box and you have your own drybox that fits 4x 1kg spools.
See IKEA box here: https://www.ikea.com/se/en/p/samla-box-with-lid-transparent-s69440822/#content
and you can use this tube: https://www.ikea.com/se/en/p/hultarp-rail-nickel-plated-90444432/ it must be cut into two tubes one measureing 32cm for the top rail and 30cm for the bottom rail.
The files contain a silica gel box that also works as a filament holder. You have to add your own 16mm steel or allu tube.
Use the hole guide to place the 8mm holes in the box for the filament guides and cut out squares (the the fittings cannot rotate), then assemble everything and use the guide to secure the filament tubes.
You can install bowden tubes with the add-on cap for PTFE tubes.