[Open Frime TV] has a video addressing this in a novel way, by creating the windings for a switch-mode power supply transformer using stacked PCB coils instead of wire (Russian language ...

Bel group company Signal Transfomer has announced its new Wireless Charging Transmission Coils (WCC) in both Single and Multiple Windings for smart car applications ... They come in two core shapes, ...

Even with the kinds of coils used in chokes and transformers for ham radio, which generally have relatively few windings, passing all that wire through the toroid time after time is a pain.