About this 3D model
I originally tried to build http://www.thingiverse.com/thing:973 , but RepSnapper disagreed with its geometry. This drag chain link is 45mm wide, 29mm deep, and 77mm long overall. The cross-section of the usable volume is 27mm wide and 25mm deep. Each link has a useful length of 60mm. It took about 45 minutes to print a single link with RepSnapper on a Mendel. I printed two in a pre-assembled orientation and they fused, but separately printed ones snapp together with a little effort.