Filament spool rack / shelf.
I used a 16mm diameter and 1.5 meter long chrome metal pipe from a local hardware store. I admit that a copper pipe with holders of the relevant color would look quite stylish. I would recommend using the middle holder for every 0.5-0.7 meters. In my case, there is one middle holder for 1.5 meters (for 0.75m), it holds 10-12 kilograms without visible problems.
The next idea, if you put spool width tubes on bearings between the two holders, it can be used as an additional spool holder for the printer.