If you've ever tried to disassemble the 3D Systems Cube3's cartridge spool you know how frustrating it can be. Much faster than unwinding all the filament.
This little tool, times 12, will let you separate the spool shells for whatever reason you may want to. I did this to quickly empty a lot of spools for B2B mods.
I printed these with 5 walls (almost solid in CubePrint) using PETG (Ekocycle slicer with file update for Cube3). You can stab these into the slots of the cartridge spool even if the spool is full of filament. Once all 12 clips are seated, you should be able to separate the two halves.
edit: I added the .cube3 file set to ABS for 2 pieces. These really should work in any material. I like this PETG because it is tough with outstanding layer adhesion. Note that the original slicer for this file was Ekocycle from within the CubePrint 4.03 app [offline printer]. Check out the file editor on Print3DForum.com : http://www.print3dforum.com/showthread.php/2098-Cube3-File-Editor