Pumping peanut butter through the Moineau Extruder is a much better test of the system than yogurt. Quick summary: Worked great! I was concerned that the gearing wouldn't handle thicker material, but it was no problem. The leakage was also a lot less. You can see the video here: http://youtu.be/4vtTN_aZ8iU

As mentioned in the video, clean up is a mess. But it's not a disaster and will get easier with practice. Probably easier with clay since it would be more water soluble. Delivering the material through a tube worked ok, but the large syringe (from my Oogoo project) needs to be improved.

There is one problem that needs to be dealt with before trying to actually extrude a shape. This occurred to me as I was doing the peanut butter test. The Moineau chamber is less than 360 degrees. That means that the progressing cavities never completely block the pressure from the supply system and thus do not independently control the pressure and flow of the material being pumped. The expected advantage of the Moineau design is not fully realized!

The answer is to extend the Moineau chamber so it has more than 360 degrees of twist. That's next. In the mean time, enjoy the extuder in action.