Toroid cores are manufactured from different powder materials (e.g. MPP, High Flux and ferrites)
but they are also made as band cores from grain orientated NiFe materials. They differ from all other types in the non-existing divisibility. This divisibility requires a more or less big air gap, which is hence lacking in toroid cores. And that is the reason, why toroid cores utilise the respective material properties in their most effective manner. They are not made for automatic production but they are wound at special machines. That’s why they are compared to other types (especially E cores) relatively cost-intensive.