In honour of the soon-to-be-released new James Bond film Spectre, our techno-weapons-tinkerin' friend Patrick Priebe has created something else that you should never try building at home. It's a working plasma "cannon" disguised as a digital watch, and is just the sort of thing that 007 might use to escape from the clutches of … well, of the Spectre group.
The aluminum-bodied device, also referred to as an "electrothermal wristwatchcannon," was inspired by Bond-based video games in which you have to shoot out light bulbs in order to move unseen through enemy territory. Light bulbs are in fact what it's made to destroy, although you probably wouldn't want to aim it at anyone's face.
At the press of a button, a 350-volt capacitor draws power from a supplied button cell or AA battery. Once charging is complete, the pressing of a second button creates a high-voltage arc within the watch, causing the capacitor to rapidly discharge. The resulting blast of heat and pressure shoots a cylindrical brass-tipped plexiglass-ended slug out of the watch at high speed, smashing whatever it hits.
In order to make it look a little more watch-like, Priebe gave the device a fake digital display by scratching numerals into a spray-painted strip of plexiglass. LEDs behind that display create a convincing glow.
You can see the plasma cannon watch in action, in the video below. Aspiring secret agents might also be interested in Patrick's previously-created laser wrist watch.
Source: Laser Gadgets by Patrick Priebe