D-Bot Extruder D4 Gear Version

I wanted to switch out the drive gear for a D4 Extruder type drive gear but found that the original design wasn't suitable for the larger gear. I kept the same overall design but slid the extruder to the right by a few mm so it would fit a 12mm diameter drive gear perfectly. I also added a few mm to the bolt holder as that had broken off on me on the original design.

This model works with the roller arm from the original extruder.