by s_p_e_x, published
I tweaked a Makerbot Replicator octave-sytle spool-holder that worked well for me for months, but had a single point of failure (the nub which kept the spool on the spindle was very small and eventually broke off).
Importing STL into Sketchup (via meshlab) made for an interesting result. But it works.
I recommend printing it on its side with support on. It doesn't use much.
PLA seems to be slipperier than ABS. I actually put a bit of graphite on the older ABS prints to help it slide.