Whats your goal as far as weight carrying ability. I personally make all my shoulder straps and hip belts. My pattern came from a pack I already owned. Trace the straps and add about an inch on all sides for the seam and shape allowance. Blue foam is a good choice, but I also make lightweight straps out of fleece. I end my straps with a triglide and them attach them to the pack with a piece of webbing sewn to the pack. Think like a climbing harness and "double backing" to attach the triglide to the webbing.
Scott
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I had superhuman powers, but my therapist took them away.