Yet another spool clip - this one is designed to be printed in PLA. Because its flexible, it is compatible with MakerBot and 100mm x 30mm spools and most likely many others.
UPDATE Jan 22 2013
I have created four different clips sizes to accommodate reels with different flange widths.
S = 3.0mm
M = 3.5mm
L = 4.0mm
XL = 4.5mm
This clip was designed using an ACIS solid in Shark FX (sfx file included) so will behave well with Makerware, ReplicatorG and skeinforge.