This is a modified version of the 2011's Moineau Pump by emmet, I've made some changes to the original openSCAD file to allow the creation of multi-lobe rotor and stator, following this guide: http://siags.siam.org/siaggd/problems/gravesen/HypoEpi3_2.html
This Moineau (a.k.a. "progressing cavity") pump can be used for many purposes, like the original, when volumetric pumping is needed.
We are currently testing our crazy idea for a modified extruder, allowing a 3D printer to be fed with plastic pellets instead of filament, and this type of "screw" is the only one that can provide a precise feed of plastic (Auger screws cannot do this).
NOTE: version 11 has been updated, some of the previous ones had bugs and/or the resulting STLs wouldn't work, please use the current one that is improved and will render correct STL files for values of "number of lobes" from 2 to 9.