Summary

UPDATE: I like this design and worked on it...made a few adjustments. Added a new STL file (earbud reel V2.stl). This new one has the same outside dimensions but has more volume for cable storage. Looks and feels better too, imho.

Instructions

ADDED a modified version: -->earbud reel V2.stl

I searched but didn't see a design like this. If there is one on Thingiverse, then credit to that person.

These JVC buds have a 2mm (2.2mm ?) cord and are about 1.2 meters (48 inches) long .
The buds go in the center, then wrap the cord and tuck the end connector into the nearest slot.

With Afinia default settings (0.30mm layers, medium speed, with a raft) it's near a 45 minute print and uses 25g ABS. The finished part weighs ~15g. Angled long-nose pliers were helpful in removing all the support from the center cavity.

Note: I use Imperial measurements and my STL files could appear tiny (3 inches may equate to 3 cm) when viewed . While some metric-mode editing software might require setting adjustments, AFAIK print software recognizes the situation and prints them correctly.
[EDIT 3-2015]
If your print software imports it really tiny, scale up by a factor of 25.4 to get the proper (metric) dimensions.

One of these days, I have to go through all my projects, create and upload metric versions...
Yeah.. like that will ever happen!
But seriously, that's what I do to create them. Just scale up by a factor of 25.4.

Earbud Reel