Look through the small devices that were used by agents of KGB some dozens of years ago.
A camouflaged gun in miniature.
This electronic listening system was used successfully until it was found by KGB agents.
The 4,5mm gun is hidden inside a lipstick.
Another small gun in the pipe
The gun fires cyanide.
A small camera is hidden inside a pen.
There is a recess in these sleeve-buttons; middle of the XXth century
A coin with a recess inside; middle of the XXth century