i used pla but i guess nylon works better.. most things are tight fit except the rotor, to the holder. need to push the 4 bearings (22 mm OD * 8 mm ID * 7 mm thick) into the rotor and knife blade, then put rotor on the bigger area side and knife blade on the small side of the holder. then try to knock the pin into each one, and adjust the rotor so it could spin. last step to put the knife blade (regular sheet rock knife blade) in the blade holder, and push it in with a screw driver. and watch out don't cut yourself then!