Inspired by CreativeTools' Universal stand-alone filament spool holder
http://www.thingiverse.com/thing:508896

Made a universal roller using ball bearings before but not satisfied, so decided to stick with my scrap hard drive as a roller. After using a roll of tape to support the spool, I made this to better centralize the spool on the disc (not perfect but I'm happy with it).

I made the base and the rod so tight so I didn't need to use glue to stick them together, but because of that I pushed so hard and almost broke the base. The center-guide cone works fine on the big spool, but not the small one as shown in the picture.

Note:
Hard drive Spindle diameter : 32mm
Base to Disc hole : 32mm
Rod diameter : 15mm
Rod height : 120mm
Rod to base hole : 15mm
**If your prints are too tight to fit, file or sand down a bit before assembling.

Update: Small center guide STL added

**If your prints are too tight to fit, file a little before assembling.

After printing all parts:

1. Push the base to the disc spindle
2. Push the rod to the base
3. Make the rod rotating perpendicular to the base disc as close as possible by rotating the disc. Adjust if needed.

Now, put a spool of filament through the rod on the base disc, then use the center-guide to move the spool.