If you have a 210x20cm space on your ceiling – like I do – then you can screw the filament rack onto it using an Ikea HUGAD curtain rod set. This way, you don't even have to cut the rods.
I used M5 threaded rods that were about 280mm long for this. If you use 350 mm long ones, you can even put in there the rolls in unopened boxes.
You probably don't need the middle element, but I played it safe. If that one wasn't there, one more roll would fit on the rack.
In addition, you will need 2 M4x15 screws per element to fix the rods.
There is also a drill template in the files.
The author marked this model as their own original creation.