I love this so hard...

[madeofmeat]

Nearly free, dirt-simple skylight illuminates slum shack housing in the Philippines. It's a 1L bottle with water in it, and some bleach to prevent algae growth. It's positioned halfway through the corrugated steel roof, with a rim of the same material to hold it in place. The water scatters the light and illuminates the whole room, as opposed to a plain hole which would only admit a straight beam of sunlight and not do much good.

It reminds me of Afrigadget, which I'm glad I have an excuse to mention again.