Re: Exhaust tube bending
Try filling a section with water and freezing it. Still needs capped ends but not sealed. Only one end needs to be sealed if you stand it up freezing it.
Caps still play a part in holding pressure as you bend, but if you can hold the column from popping out the end it works.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.