A simple set of filament reel rollers small enough to fit in your pocket, but big enough to do the job.
OpenSCAD was used to model the reel roller, and the design drivers are:
Use the least amount of non printable hardware as possible.
Easy to set up and put away, as working space is limited.
Small enough to drop in a box for storage and transportation.
To fit any size spool.
All the parts available on Ebay.
To make a pair of reel rollers you need to print four sides, two per unit.
Full prject details here http://airtripper.com/313/pocket-reel-roller/
8 x 608 ZZ [8 x 22 x 7] Roller Skate Ball Bearings. Very cheap off Ebay.
8 x M3 x 30mm Hex Head Screws. Ebay.
16 x M3 washers. Ebay.
8 x M3 Nuts. Ebay.
3D Printer Filament.
Hex Key to Fit Screw Heads.
Pliers or Spanner of some type.
3MM drill bit to clean out the screw holes in the printed parts.