The title of this Thing should be "Hypocycloidal - Schmidt - Moineau Paste Extruder", but that's a bit too long! This design uses the Hypocycloidal Drive from these two Things: http://www.thingiverse.com/thing:79231 and http://www.thingiverse.com/thing:81879, couples with a modified version of the Scmidt Coupling here: http://www.thingiverse.com/thing:233667 and builds on the design of the Moineau Extruder here: http://www.thingiverse.com/thing:15538. The result is an extruder design driven with a NEMA14 stepper ready to mount on your X-carriage and try out. See it in action here: http://youtu.be/KyuY_WrrCKw TODO: Now that I have a working design, I need to try putting various materials through it. I have pumped yogurt just fine, but need to try more viscous (stiffer) materials. Here it is pumping Peanut Butter: http://youtu.be/4vtTN_aZ8iU One problem to be solved is the leakage of material into the coupling chamber. Still a problem, but not over-doing the supply pressure helps. Another challenge is just how to deliver the material to the inlet. ** Needs a better method, but the tube part is OK. Did I mention that this is a Work in Progress? Please try it out and contribute the results of your experiments!See my earlier Hypocycloid things for building the drive. Use a 5 lobe lower case, a 5 lobe output, and a rotor with 5 lobes on the lower section and 4 lobes on the upper section. That will give you a 4 to 1 gear ratio and is what I've used so far. It's easy to get a higher ratio if needed. While most of the design is done in OpenSCAD, the arms for the Schmidt coupling were designed using FreeCAD simply because it was so easy. My re-design of the original does two things: 1) the plastic fiber pivots are replaced by 2-56 screws, washers, and nuts. 2) the upper and lower coupling disks are modified for my purposes. There are two versions of the Coupling Cover. One has windows in it so you can see the coupling in operation (it's amazing) and one that has no windows for safer operation during printing. Pick your favorite. The profiles for the Moineau chambers were created using a Python script I wrote. It is available if anyone would like to have it for creating custom profiles for pumps having fewer or more lobes. Since this is a Work in Progress, expect to see some updates as I experiment.