The Positron V3 uses the heater cartridge as a dowel pin to prevent the brass insert from falling out. Then the heatbreak screws in and bottoms out on the side face and the nozzle bottoms out on the top face of the insert. 

I'm wondering if something similar could be done for the corners of the trangle material path. I can't think of anything at the moment that's not even larger than the 40mm edition in the previous log, and I fear that PCBWay would charge for every sperate entity.