By OH6DC
Too much alcohol is bad for health and CW skills. Therefore it is maybe advisable to only buy spirit for using the bottle as a telegraph key. (Use the liquid inside for cleaning the contacts of your other CW keys.) Follow these modification instructions:
Attach two strips of aluminium tape to bottle threads. Then connect the keying wires by using a cable tie around the bottle neck.
For improved keying performance, aluminium tape should be added inside the cap (right side) as well as a piece of insulation tape (left side).
Backside view. Not much "cleaning liquid" left.
Bottle cap keying demonstration here: