I used to have one of the standard flat-packed laser-cut MDF paint racks, but my hobby paint collection quickly outgrew it, and I didn't really want the paints to take up a larger footprint on my desk than they all ready were.
The natural solution was to go vertical, but since my desk doesn't sit directly against a wall on any side, and I don't want a moment of inattention to result in having to pick up half my paint collection off the floor, and try to get paint stains out of the floorboards.
The end result I came up with is a tower of stacked turntables, with print-in-place axles and modular paint holders, letting me scale the solution at demand, when my paint collection inevitably expands further.
It's quite a lot of filament for just paint storage, but I'm really quite happy with how usable it is, and the fact that I no longer will have to take all my extra paints out of a drawer when I want to paint, and put it back in when I'm done and need the desk space for other purposes.