I love scratch builds of the jetpack & this looks great but based on what you stated, I am curious as to how much this weighs? It looks to me like it would be really heavy.
I only see the upper hooks & if you don't already have it you may want to try & incorporate a lower support bar to help the jetpack rest on so it will take some of the weight off your shoulders with a waist belt. This really helps distribute the weight & add to the comfort. This may help the pain in your shoulders.
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