Dry Box Rod / Spool Holder with Backing Plate.

Use 1.25 PVC (That's 1.66" actual OD) and M4x16 bolts and nuts.

Redrawn from someone elses design because I prefer metric fasteners.

Recommend this for filament pass through https://www.thingiverse.com/thing:3397576

And this for holding a humidity sensor in the box https://www.thingiverse.com/thing:3394439

I used a 44 quart ziplock weather-shield storage box, which gave me 16" of usable rod width which is 5 spools with some room. I added a shallow version that adds another inch in