Space Invaders Carriage (Eustathios)

*Updated version of this extruder can be found [here](http://www.thingiverse.com/thing:1322641)*

This is an experimental extruder design that may be compatible with some [Eustathios](https://plus.google.com/communities/108524206628971601859) printers (I'm using [Eric Lien](https://plus.google.com/+EricLiensMind/about)'s [Eustathios v2 Spyder](https://github.com/eclsnowman/Eustathios-Spider-V2) variant). This extruder is designed to switch between bowden, direct drive [Gear Head](http://www.t