I’d think I would have to do with the lift to weight ratio. Essential theres a few ways of going about it. Poly tubing with coils or copper tubing. Poly tubing would be the lighter option. Though the copper tube being the strongest option. Say you have a final ring filed with magnetic fluid. It weighs 2-3kg. The kite would need to be able to lift that with all the tethering gear. Even a ball park figure a 6-1 lift ratio. would need a kite able to lift 6 times its own weight at variable wind speeds.
I’m reminded of box kites usually quite bulky, but also very ridged. But have loads of lift. The more I think about potential design direction I realise there are many ways to go. Even a spinning box kite. With the hollow rings inside. Using a combo of the Magnus effect. With lift surfaces. The windswept design definitely would suit this as an application. With a large sweeping diameter.
I don’t think it would take all that much to achieve it.
I can recall hollow generator designs with a magnetic ball bearings. Used by joggers. They used poly tube and coils. I could imagine copper tape being used to wrap the tubing and a rectified converting it from dc to ac where required.