Efficiency targeted features:

- magnetic bearings, maglev using permanent magnets to suspend the z axis and keep the x-y position of the shaft stable.

- omni directional wind harvesting, either with a helical vane or impeller design / fixed wind guides.

- automatically attenuated / tuned field position to reduce cut-in speed, something like a mechanically actuated centrifugal governor, acting as a lever to change the stator positions and add a flywheel element.

Cost down targeted features:

- aside from magnets, favor durable, inexpensive materials and construction methods and materials, such as marine plywood, polypropylene, pvc (with suitable UV protection)

- bespoke analog circuits with minimal BOM unless more complex and costly solutions provide better efficiency.