I've managed to make a small rain collector (and even test it). It also has an additional feature: it FILTERS the water.
Find below the pics (as usual, baaad quality - maybe I'll get nicer ones during the week-end):
1) Parts of the collector:
2) The filter contains (from top to bottom - don't forget that what you see as top is actually the bottom): cheese cloth, small pebbles, cheese cloth, bigger pebbles:
3) Partially assembled:
4)Fully assembled:
And the movie:
https://www.youtube.com/watch?v=iNUmzKKNryA&feature=youtu.be