Thanks to K-Tiger, I have a solution for the shoulder straps...
Hockey Tape!
I had seen the tutorials on making plate carriers and pouches with it, but it never dawned on me to use it on my rucks until KT mentioned it. It is a much better alternative to elastic or ribbon and it's the best I can do until I have a way of producing sophisticated vinyl or soft plastic shoulder straps.
Here are prototype photos. The shoulder straps will receive some more refinement, but you get the idea. Please excuse the poor lighting. I wanted to get this update done when I had some time. I'll post more photos that show the pack details when I can.
And here is the Rucksack with the LAW:
I wasn't thrilled with the shape of the 2-quart canteen. I had it revised and an updated version will be printed this month.
This week I'll be working hard on casting these and making consistent shoulder straps. I hope to have copies to sell by the end of this month.