The last thing I personally built was a display board for my business.
It was something small enough to tote around to home shows.
Basically a 3'x 3' roof with rain gutter system.
It was functional. Pretty neat. I ran some clear plastic line under the ridge cap that had holes in it to simulate rain. I hooked up a swamp cooler pump to the line and set it in a deep pan.
The water would run down the roof, into the raingutter, out the downspout, back into the deep pan.
Edit: probably a year or so ago.