Inkscape extension to create a living hinge

This is an extension that installs in Inkscape. It adds lines to an Inkscape document that will result in a living hinge when those lines are cut, usually with a laser cutter.

An example of using the living hinge is in the file pencil_box_2side_w_divider.svg

5/26/2015
Version 0.2 has been uploaded.
Changed inkex.unittouu to self.unittouu
and inkex.uutounit to self.uutounit
to make it work with Inkscape 0.91
Thanks to Pete Prodoehl for pointing this out.