I bought a Benzomatic 2500 torch, heater and soldering iron multipurpose iron. See website. https://cdn.thingiverse.com/renders/c9/20/b1/cf/43/b47429982cf801a896f99982e4ef359e_preview_featured.jpg I found out just by luck, that if you take off the soldering iron tip the threads fit the .4mm nozzles on makerbot printers. I just screw it on and let it burn till it stops smoking and the everything is clean. I use a little lube on the threads to get them to go back on the extruder.