Yep, you are probably right about the rare stuff. You know, what I would like to see is a partnership with an accomodating mill to produce fabrics we could go nuts with. Something like Malden mills did with Polarfleece, etc. - working with folks who could appreciate it.
In general, if BPL were to do something like that, it would be better to go for a fabric that would let BPL corner a nich market... not only for the fabric but also for products using it well - as well. That would just be smart business. There is no use competing for a DuPont franchise on some new insulation or fleece where the potential market is huge and global. It just won't wash. But a nich product for a nich market would be just right.
As for hardware items, small hungry companies often will work with small buyers. Back longer ago than I want to remember, Fastex was very accomodating and traded prototypes for feedback. I still have some of the poorer efforts. Ought to bronze them.
Then, I can pipe-dream. For example:
First, how about a pack fabric so light that it would scare away uninformed buyers and conventional manufacturers? Like your Cuben pack, but really strong.
We have seen Spectra/nylon grid fabric in 4 oz weights and PU coating for light packs. Spectra with its low stretch would probably work better with polyester which has a similar modulus of elasticity and furthermore holds shape better, absorbs less water and is more UV resistant than nylon. A tight Spectra grid would more than make up for the polyester's lower strength. Then impreg and coat (both) with silicone so it won't start smelling like something the dog sicked up in a few months. Think of the weights you could get with good fabric strength and better performance than our good old 1.35-1.4 oz. silpreg. I'm willing to bet you could use 15D polyester with a 20D Spectra grid (Specrta deniers are lower than some other yarns, as I understand it, because if its lower density) and get a sub 0.7 oz fabric before coating. With a heavier, really waterproof silicone preg and coating the weight would probably go less than 1 ounce per yard for a usefully durable fabric for light packs - a fabric that really would be overkill for shelters... although conventional makers might find a use for it as tent flies and floors. If they could tear themselves away from polyurethane - which puts a 'use-by' date on every item containing it.
Then for shelter, I dream of something that, again, that would seem too light to work... and this one could be so light, no conventional manufacturer would be likely try to use it like we expect to.
Conservatively, a 1/16 inch grid of 10D Spectra and a web of 10D or microfiber polyester ought to be tarp worthy and weigh with silpreg less than 0.5 oz. Or a modern mill might even be able to make an intimate mix of yarns where the poly would be more like a filler with the Spectra to produce a flat weave closer to 0.3 ounce. Such fabrics might give Cuben a run for its money for both weight and strength. And should be sewable with more or less conventional methods available to MYOGers.
We talk a lot about fabric, but there are a couple of things that really add weight, buckles and straps. How about:
Tablar buckles and other fittings suitable for grossgrain ribbon. UL packs do not need much more than good nylon grossgrain, but no currently available tablars that I know of will work with it. Another angle is adjustable buckles or fittings what would work like tablar buckles with parachute cord or other small line.
And while we are on grossgrain, how about getting a mill to make a Spectra or aramid grossgrain - either pure or with a polyester fill. Aramid MuleTape is unbelievable stuff, and flat braided or grossgrain straps of similar material would certainly be adequately durable. To say the least.
The issue of patterns has been mentioned, and I'm all for that. Clothing in particular is my least favorite thing to prototype and make.