This is an openscad rewrite of the clever filament holder by Boardofdenver, now fully parametrized to accomodate any diameter. With the customizer you can tweak all the geometry: thickness, number of arms, segment lengths, angles and so...
Here is a video of the thing: http://www.youtube.com/watch?v=tNVpsIQXVbE
I also added two holes on each branch to lock the other end of the filament (check the close-up with the blue filament).
You will find two predefined geometries, you can mix the hubs and arms but use two same hubs (and of course one kind of arms!)
By default they rotate on a M8 rod (eg. with http://www.thingiverse.com/thing:137602 for the ultimaker)
Printed with ~2mm walls and 30% infill. Use more arms for bigger or heavier spools, 3 sets of arms is usually enough (ie. 3x2=6 parts, since the branches are all the same). You need also two prints of a given hub.
Note that you can also define a fake spool temporarily to adjust the arms.
I use it with my minimalist spool holder and my customizable thumb nuts (check the references).