Emergency stop punch button

Sometimes I feel the need to quickly power off my machine tools when working on it, and have installed a "remote" stop switch on the lathe that I grab and hold in the hand when making some critical operation. Just a press and the motor is dead.
My lathe and my milling machine have already latching emergency stop buttons, but sometimes, specially when working on the lathe, I want to stop the motor without move my body to reach the original commands and without have to keep the switch in my hand.