Hopefully, this will reduce the use of virgin plastic for creating art pieces in 3d printing community and you might be able to create beautiful and useful things out of waste plastic while cleaning plastic waste from the environment.
It's a profitable business.
I worked on this in my free time during quarantine.
I want to make the project more accessible so people around the world can develop local recycling unit. There is lots of work which needs to be done including making parts more standardized, demonstrating how parts fight together in a visual way and also have a microcontroller firmware to control diameter of filament. I don't have much experience with microcontrollers but I've ideas, so we'll see.
Any idea how they are doing it?
Wood drill has continuous flight depth while extrusion screw has 3 zones. In compression zone, flight depth is gradually reduced to compress polymer.
Other than this, I think you'll have problem with finding reasonably straight wood auger drill.
With precision machine barrel and screw, screw will not touch barrel wall.
You can experiment with wood drill and steel tube but I doubt you'll get consistent diameter filament with it.
If you fancy making cheaper one for small scale/personal use, try this one: