I think the bunker is a bit of overkill just for PLA but for Nylon or PVA its a great idea...
Now the question is how to make a cheap and homebrewn version
It have a giant container (60x40x75 or something like that) that where I keep all my filament in (I have quite a few reels).
Besides the filament that container also has about half a kg of silica bags in there
So far my filament is still okay.