SaveTheWhales said..Kam...
There's 2 simple ways to explain this for those with little experience in the variety of 'brand' swivels...
1. How many years have the experienced kiters world wide been asking for a bar that's got this this and this... Quite simple and even gave design tips and pics !!
All we got was 1 out of 5... Ever heard of people asking for soft bar ends ??
Which top brands have them.. How many years did it take..
So you can see it's not "Rocket" science and there definately not that skilled or we would have bars with everything that makes it perfect - including a swivel that does 'Not' stop working, which instantly makes a below bar swivel 'Obsolete'
Mutany have got the Swivel right (3+ yrs still smooth on mine) but not some other parts... get the drift..
2. You pay between 3-700$ for a new bar, yes top dollar for something that's around factory 50$ !
In comparison why would you buy a new car with a "Hand" crank. Everyone knows the auto cranking starter motors exist - but they can still milk, the ignorant..
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As for the width of the body, we are talking a 1cm difference, not much - but a proven 3+ years twist free difference

Sealed bearings - ever heard of general maintenance of your kit that could save your life ?
If not, then i guess you never clean the sand out of your below bar swivel or chicken loop either

Not sure I follow you totally...
1. You're dealing with things like patents, brand recognition, and paying off the set up costs of the components. There may be a better way to do things, but jumping ship may not be in the best interests of the company.
2. As above, the cost of components that are ordered in bulk, no doubt, needs to be defrayed by selling them. Secondary costs like R&D, advertising. And probably the biggest - injection molded parts; cents per unit but tens of thousands for the mold.
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Well, you can still buy twin tub manual washing machines... you might be right. Luddites everywhere...
My thought was of the widths of the arms. I guess if the body increased in width to compensate, it'd be no more inclined to catch lines but over-all bulk and weight increases bother seem people cf. below the bar depower, "it's just cleaner brah."
You don't like sealed bearings? You prefer to oil stuff?
I check swivel is free when I lay out my lines, pulleys are free (every now and then) when I attach lines, QR freely operates when I hook in to launch. I even check the QR on my leash...
Gonna be interesting to see how 3D printing will change the game.