I use a cafetiere to make strong coffee.
Sometimes the pressure developed when plunging the filter is really too high for safety.
Today’s invention is a low-cost, pressure-regulating cafetiere filter.
There is a seal unit (red) and a fine mesh (blue), as usual.
In addition, we have two steel discs with radial segments removed from each (pink and green). Turning the pink relative to the green, exposes more or less area for the coffee to flow through.
When pressing down on the pink sphere, if it stops moving down, rotate the sphere about the vertical axis. This will spin the pink disc relative to the green disk (which is in contact with the coffee grounds).
This relieves the pressure and caffeination can continue.