Several weeks ago, I worked on this all aluminum extruder for 3D printing clay. This was a fun project that I banged out in an afternoon. I even gave my studio South Bend 9" Model C a tune up right before I started working so the process went fast. I'm really starting to get settled into my studio which is really good. I tried to show the steps here that I took to create this. I use a 1/4 drill bit as an auger driven by a Nema 17 motor, that helps advances the clay down the tube along with the air pressure.