[Igor Brichkov] shows us how to make a core rope memory using a set of ferrite cores and wire. This was famously used in early UNIVAC computers and the Apollo guidance computer.

How hard can it be to create your own inductors? Get a wire. Coil it up. Right? Well, the devil is definitely in the details, ...

You can call that plastic cylinder a ferrite bead, a ferrite choke, EMI filter, ferrite core, or ferrite block. Whatever the name, it serves the same purpose.

Pulse’s PA1894NL and PA2080NL series use a single-turn conductor with a ferrite core instead of a multi-turn conductor wound on a powdered iron toroid core.