YAFR (Yet Another Filament Roller)

I wanted a top-loading filament spool roller solution to go in a dry box (http://www.thingiverse.com/thing:1359419 http://www.thingiverse.com/thing:961881), looked at several existing designs and decided to make my own to optimize a few things for my situation/tastes. Primarily, I wanted it as thin as practical - so I located the "spool keeper" plastic on the inside of the spool, it sticks out about 2mm from the bearing - not enough to rub the filament on the spool, but enough to keep the spool