Why does anyone want to block current/electron flow? There needs to be an answer to that.
It would be great if Stan Meyer showed a circuit diagram, but he didn't. It would be madness if he gave away his invention.
a FBT is a choke, in that current passes in 1 direction only. As a manufactured component it is a semi-conductor. Try measuring one.
A diode blocks current.
FBT description is a "coupled Inductor"
Les Banki studied the Japanese patent of the NGK Static Induction Thyristor. Les came up with an equivalent circuit because the NGK SITh was unobtainable.
Les circuit had a 1:1 ratio FBT, coupled Inductor. <That was an interesting addition to study. He did not go into depth of his thoughts.
Les contributed many working circuits for electrolysis and ignition control for Hydrogen motors. They may still be online.
Les Banki was chased off the internet. Why? All he did was present an equivalent circuit diagram 10 years ago.
https://www.overunityresearch.com/index.php?topic=2578.0