We wanted to use the same 1.75 mm plastic for both printers. Also, the previous inbuilt extruder did not reach high enough temperatures and the heating resistor  burned out. In addition, the plywood parts of the previous extruder became brittle due to proximity to the heat. nightshade, pwf and Simas teamed up to build a new one.

They used E3D hotend parts and nozzle and a custom holder that fits on TAZ printers. Here’s a blueprint by pwf, CNC-machined out of aluminium by Simas:

The blueprints are also available on Github.