Some art supply or plastics stores will have Polypropylene (PP) in a thin sheet. Old portfolio or art storage pouches are often made of it, as are those Asssavers fenders.

It's good and pliable but when properly encased can be quite stiff.

I would agree with Dr Welby - I believe the Ortlieb classics are a vinyl coated polyester, coated on one or both sides (you can tell!) While some bags just have a waterproof polyester on the side panels, not nearly as thick of a coating at the vinyl. Saves a great deal of weight.

Not exactly a treat to sew or seal. If you had access to a ultrasonic machine (sonobond) and some Bemis tape you could make quick work of this fabric.

Hey guys, I'm doing my product design 'thesis' project around a good shoe for hiking and biking. I've read most of the discussions on this forum around pedal choices and conversations stemming from specific footwear, but so far these insights aren't pushing me to take the kinds of risks I would like to for my last university project. I posted a few questions on reddit but thought some here might be up for digging into them too.

1. What is your level of experience?
2. How long is your average trip?
3. What footwear do you bring on a bike packing trip?
4. How much time do you spend riding, how much time walking/hiking...on an average day?...at extremes?
5. What sort of issues do you have with footwear?

Any information obtained here will be presented anonymously, for my own analysis and ethnographic research.
I appreciate it and hope to share some bikepacking bags I'm working on when I get some room to breath from this research!