precision paste extruder based on screw frosting device

This is an amazing paste extruder based on one I've been working with with a HYREL 3D printer. It uses a geared down stepper motor and a paste (frosting/clay) extruder you can find many places. There is a patent on the frosting extruder part, actuated by a screw/plunger (USPTO# 7413429 B1, 7416400 B1, and 7476097 B1) but as far as I know this just means you can make/sell this part. There are many sources that I've seen (amazon, walmart.com) for this part of the extruder, but as far as I know, th