I've been promoting the use of cool white flickering LEDs as the absolute cheapest and easiest way to simulate a welding effect. Then I was asked by a YouTuber if I could make the effect periodic--weld for a few seconds, pause for a few seconds, repeat.
I came up with this solution. It's good for those who are not electronically inclined since it makes use of a cheap ($5) flasher unit from eBay, plus a flickering LED. Oh, and two resistors.
There's also an option to include an 0402 SMD LED for a point-source effect.