In Volo Guide on Monsterspage 81, the following section is included in the Mind Flayer subchapter:
Flayer Magic Objects flayer
Some crook colonies have developed the ability to create or modify certain types of gear by giving them psionic energy. Swindlers of the spirit craft magic items that only they or their thralls can use – a sensible security measure to prevent enemies from turning the illithids' creations against them.
It then lists some of these magic items on page 82, such as the mental bladebut that does not seem to go into more detail about how these elements are created / modified, or how long it would take.
My question is: How long does it take for a spirit flayer to create such a magical object? If you give a friendly-looking flayer a non-magical sword, how fast can it make you feel good? mental blade?
I am mainly interested in 5th information, but if there is any information about it in previous editions of D & D, I will gladly accept it as well. Any additional information on How such articles are created / modified are welcome, but not necessary (since I am mainly interested in how long it will take).