What is it?
A small gate latch for our chicken coop.
Scale up for imprisoning larger animals/general use.

How well does it work?
Surprisingly well! Closes easily and doesn't open in the opposite direction.
Strong enough for most purposes.

Any problems?
The plastic hinge-pin thingo is hard to print at this small scale, a cable-tie or anything around the right size should work.

Other
I hope to make some genuinely useful items for 3d printing. I'd love to hear ideas for things that haven't been done already.