Thank you, Mojo.
I had considered that. But it might need to be a silver tube to sound okay.
I would also need a way do describe it precisely in a way that could be converted to 3D printing instructions.
I appreciate you suggestion though. It is great to be thinking outside of the box.
I made a foil tracing of one, that I plan to take to my flute mechanic to see if he has any suggestions. He was able to improvise a Bb footjoint for me, so that is a possibility.
In the meantime, I am still open to purchasing a used Foster Extension.