The trickiest part of any shop prank is making the fake gear convincing enough that nobody gets suspicious, and the maker handled that by cutting sparklers down until they passed for ordinary welding rods. Getting the length and look right seems to be where the effort went, and it paid off, since the target went ahead and tried to strike an arc with them without a second thought.
The setup itself is simple but well thought through. Allan Lesko handed the doctored sparklers to a coworker and asked for a few tacks on some I-beams, and the welder went at it with an arc electrode holder on a black cable, a blue helmet, and protective gloves. The shop around them had a chipping hammer and a rolling toolbox in view, and a big welded steel frame with white writing, including 'Do Not Move!' along its top edges, sat up front.
What stands out is how quickly things went sideways. An explosive pop and a fireball flared up near the tip, and the welder dropped the tool, flipped the helmet up, and laughed. It took a couple of sparklers before anyone worked out something was off, and the rest of the crew cracked up too.
The obvious trade-off is that this is not something to copy. The maker says so outright, warning people not to attempt it anywhere. Fair warning, honestly given.
Project by Allan Lesko. Watch it on their YouTube channel: