I've spent an embarrassing amount of time looking at all of Bill's creations. I've been lurking on this board for about 6 months now - finally registered, and followed his threads over at whiteblaze and backpacking.net as well. I've checked out Rodney's packs, even considered having him make one for me, but what the heck - this is more fun. And, yes, my finished product should look very similar to the G6.
I already have the main pack body ready to go - I'm really just looking at strap ideas, and strap attachment methods. I think that I can have a slightly padded shoulder strap - Vick, the auto foam you referred to sounds perfect, so I'll check local shops - and still come in with a pack that weighs 6-7 ounces or less. Those of you who have made packs, or who have attached straps to packs before, did you just bar-tack them on? Obviously, for light loads, that's more than enough reinforcement, but while I'm at it, I thought I'd come up with an integrated, slick-looking attachment method. I think I may try and have the straps attach to the inside of the back of the main pack bag - I'd leave the back panel a little lower than the other side panels, then I could attach another piece on top of it to bring the back up even with the sides and front. The extension collar could then be attached to this now-level area. Anyways, I'll post pics once I get some more time to work on this.
Roger - I second the motion - I'd love to have more details on the material you referred to. So far, it sounds like you really have some unique ideas, and my interest is piqued.