Another user suggested the Atlantic Mitsu 5-Tier Storage Rack, sold for storing CDs and DVDs, as something good for 1KG filament spools. After buying four, I realized that I could combine kits to make three eight-tier racks that would more efficiently fit my available space. I then ordered a fifth but realized it didn't include enough of the full-height side pieces, X-shaped, to build a full eight tiers. Rather than buying a sixth kit just to use two of those X-shaped sides, I designed my own.
Print in PLA with 0.2 layers, 6 walls, 10% infill. I recommend enabling supports - though the recesses can be bridged, they're cleaner with supports.
The author marked this model as their own original creation.