One of our modellers made a model of a factory building
and wanted a flickering blue light to simulate welding.
I used five flashing blue lights, operated either by a push-button,
or by an on-board switch. The button gave single flashes and the
switch produced a flickering light once the leds had got out of step.
A mini speaker salvaged from a toy made clicks to simulate welding.
The board was powered by a PP3 9V battery.