Sample Filament Spool

Have a few 15m windings of sample filaments and wanted a easy interchangeable Spool that is max 6" in diameter and would easily accommodate the sample filament winding.

Here is my spool suspended above my Taz using inkjetsux's Simple spool mount for Taz
http://www.thingiverse.com/thing:753692

This accommodates both 3mm and 1.75mm filaments. Just need the make sure that the filament coming off the spool is in the direction of the arrows. Join the 2 spools together and twist to "lock" int