Note: chances are small that you have collected the same type of trash as I have got, so the presented thing might be only useful as an initial idea of your own spool holder design to enrich thingiverse with your own idea, in addition to hundreds of other spool holder designs available there.
At least once a month my chief is very unhappy. He arrives for about a week to our office to interchange the ideas and resolve the issues, and he is really upset if a whiteboard marker doesn't give him enough color to express his visions on a whiteboard. Sometimes I throw out those bad markers, but not this time, when I've got a background problem to resolve: to build a filament spool holder that will not take a space which I don't have, and that can be temporary hanged somewhere near printer. So, the idea came to my mind, and I decided to give that marker a new shiny life in a world of 3D printing, as a spool holder core. I waited till weekend and started to implement a spool holder around the marker. I cut off a top and a bottom of the marker, found two relatively suitable bearings (having 8mm and 13mm diameters outside), and designed and printed simple adapters for the marker. Then I have found two metal angle clips which I had previously bought in local hardware store, cut off a part of one of them, threaded M3 holes for connecting clips and bearings, and assembled everything together with M3 screws. In order to make the spool holder to hang perpendicular to the surface I have attached to it a piece of organic glass. To not scratch the surface of cupboard door where I want to hang the spool holder I have glued a piece of a soft puzzle mat with a double sided sticky tape to the organic glass. I have found a latch hook from an old camera case, and connected it to the spool holder with spare cable ties left after assembling RepRapPro Mendel kit. So, as a net result everyone are happy: my chief will be happier, because he will never accidentally grab this particular non-working marker for showing his idea on a whiteboard; a waste management company will be happier because less trash should be handled; and last but not least: I am now a happy owner of a reliable spool holder that is easy to install, and that takes virtually no space. So, modestly speaking, it's a brightest implementation of win-win strategy in its glory. :-)