I just upgraded my printer to a dual extruder, with the ultimate goal of printing vibration-isolating mounts with a combination of ABS and ninjaflex. Apparently ninjaflex adheres to ABS well. The photo above is my first dual extruder project -- it's a case for the rctimer ground telemetry module. The body and cover are black PLA, and there's little clear PLA light pipes printed into the cover over the LEDs. STL files attached.