Hi all, interesting thread
To answer the SwampStick question, I have in fact perfected them with the addition of a soy based tile sealer at the bottom inside of the mounts. I have also had good results with the use of water absorbing polymers inside the mounts.
It was good timing that I came across this thread. I just finished installing an extruder I had built. So far I have had 3" and 6" dies built, but I can now extrude those very tubes you are interested in.
6" diameter, approx 1/2" thick, and I am limited on length by the height of my kiln so nothing longer than two feet.
I am planning on creating a custom mount creator type web page where you can pick a tube diameter, length, add a base, add a glaze, wax treatment, texture, or about anything else you can think of and I will build them to your specifications.
I'll be testing it this weekend so I will take some pictures. If you have any other questions regarding the SwampSticks or an extruded terracotta or white clay tube, feel free to contact me.
Kind regards,
Jesse