It may be possible if there is a ptfe tube with 4mm OD and 3mm ID. by looking at the parts i got now, you can maybe get away with drilling 3mm hole in the part with "push" fitting on top. it's only 2mm for 1.75 filament. the "pipe" part and all the way down to nozzle is 4mm to be used with ptfe tube. but i don't think it will be any good without the "4od-3id" ptfe tube, as soon as 3mm(2.85) filament gets down to the nozzle it will melt and creep up the heatsink and pipe because of all the spare