Gondola for v-plotter/polargraph

This is my take on the Gondola for a v-plotter/polargraph machine

Its meant to be light weight, use as little filament as possible, have the pen at the centre of the pivot point, not require much in the way of additional hardware (no big bearings needed), be quick and easy to assemble/disassemble and have a push fit pen holder so I can do quick pen changes.

Pen holder/organizer: http://www.thingiverse.com/thing:1393182
Pen depth setting tool: http://www.thingiverse.com/thing:1393200