This is a bulkhead fitting I designed to add drains to a series of buckets/troughs. It is designed to attach lengths of (garden) hose to the outlet barbs.
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The drain can fit through a 3/4 to 1 inch hole through any flat container wall up to 1 inch thick. (Swimming pools, barrels, ponds, fish tanks, or whatever you've got.)
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The drain is what I call "first surface" (more on that in the instructions tab) which basically means it looks interesting and is printable without additional supports.
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This can also be found on my projects blog, here:
https://theheadlesssourceman.wordpress.com/2015/04/24/first-surface-drain/

This model was successfully printed on Makerbot using PLA with 20% infill, 2 shells,, 0.30 layer height.
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You'll need to cut the support fin(s) off the barbs with a razor blade and/or file after printing. (See photo.)
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"First surface"?
The original design was the obvious solution of a dome with holes in it. The hollow cavity inside led to printing problems and attempts at slicing were messy and cumbersome. Then I got the idea of using a set of vertical fins to prevent material from dropping down inside, and thus providing their own support.
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The algorithm for this is pretty fun too. What I did was, knowing the maximum hole size I wanted (2mm), I determined that circumference=num_fins*(fin_width+min_hole). Therefore, I just back-calculated at what radius the gap would be too big and doubled the number of fins at that point.
(Interesting geometry problem that makes an interesting design. What more does a nerd need, right?)