Laser gates and slow lasers:

I’ve found that home sink and bathtub taps running water at a low flow into the drain make a great ‘base’ sound for laser ‘gates’ (security grids or fences, sci-fi barriers or doors made of “light”), or ‘slow lasers’ (“mining”, “welding”, “drilling”). Pitch shifted and then double-/triple-tracked along with a bit of electrical buzz finishes out the effect!

– Erik Nielsen