Drain with 1/2in pipe threads.

This drain connects through the wall of a container into 1/2" NPT pipe threads.

NOTE: You may have to use a spacer with thin walls as the pipe threads will get tight before contacting the surface.

This can be found on my projects blog, here:
https://theheadlesssourceman.wordpress.com/2016/01/02/drain-with-1-2in-pipe-threads/