Rigid chain

EDIT 2017-04-29:
I'm adding a zip file with the .scad drawings and two .scad libraries you need to add in the same directory to use some module.
those libraries are:
-a pin library slighty modified by me, but I don't remember which was, maybe this: http://www.thingiverse.com/thing:33790
-a herringbone rack library slightly (and badly) modified by me to eliminate the body. the original library can be found here: http://www.thingiverse.com/thing:6011

The code has comments at the beginning