Genesis

Delrin will definitely work but I'm not sure you'd actually get LESS weight out of it. Acetyl (Delrin's "technical" name) is pretty heavy, as was noted.

If the cannister exterior serves as a focal point for intentional condensation in the design, however, you're going to lose that going to a plastic. How much this would affect the unit is something I couldn't quantify - but its a consideration if the can is intended to serve as a condensing surface before the gas passes through the scrubber (if I'm understanding the gas flow correctly on the Meg, this would potentially be the case.)

It also isn't going to be cheap. Delrin is quite expensive stuff and buying a rod in this diameter (if you can even source that) is going to make you CRY. Running a boring bar down it isn't going to be the easy way out of this - it works for light cans but those are a LOT smaller.....

I suspect the answer there is that you'd need to be able to cast it - not impossible but pretty big bucks, and thus it would only make sense if you're makling a lot of them. Aluminum tubes are common items and tigging a plate on the end to close it off and finishing that is fairly pedestrian machine-shop work. Casting acetyl is not.

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket