Those last few meters of filament on small-diameter rolls drive me nuts! Coiled so tightly I can barely get it off by hand, it always causes problems for my printer.
Tired of trying to uncoil and straighten those tight little loops by hand, I created this Filament Straightener. It is, obviously, modeled on wire straighteners, but uses printed parts and is sized for filament. Pictures show before and after of tightly coiled filament. The after was put back on a reel for easy printing and worked great!
This design was done using FreeCAD. As an experienced OpenSCAD user, I find FreeCAD a very satisfactory alternative that I am choosing more and more often for new designs. The FreeCAD files are included; STEP format files are also included.
This is similar to, but not derived from, thingiverse.com/thing:30733 .