This $67 wall mount electrical wire spool rack, will hold 24x 1kg spools of 3D printer filament, with easy Dremel mods. See my review on the product page for details on the modifications.

This thing will contain all the printable parts and pieces, to fully enclose the front of this wire rack, to use it as an oversized dry box. Currently only the corner pieces have been completed and uploaded. You'll need two printed as is in the STL, then two more printed, mirrored on the X or Y axis (so the flat part will face outwards on both sides).

The slot/groove on the corners, are to allow a ~0.8mm sheet of PET plastic to slide in from either side, to seal the face of the rack dry box. The top and sides (created by the corners) are expected to be sealed with thin PET sheets and gorilla crystal clear tape. The bottom pan will be filled with rechargeable desiccant beads.

The double decker shelf will hold two RaspPi sized single board computers. It bolts on with the original rack hardware, to the bottom side corners of the rack. I use two of them to hold four Orange Pi Zero 3s, as OctoPrint nodes.