Had some 23 mm ID aluminium tubing and an auger that was 23mm diameter. I put a goove in the top of the auger and then tapped a hole to stop the auger moving up and down.
The pipe is to supply granules to the auger .
The set up moved polymorph down the tube (And up if you reveresed it!). I then added a heated barrell and a 3mm hole and set it going and it made a small lenght of 3mm ish rod but it was very uneven and when I came to restart it from cold a plug had formed meaning I had to take it all to bits again.