A table-top mobile of a fisherman, repeatedly throwing the line towards a tree. Driven by a sinking weight, it keeps moving for several minutes.
Free plans and construction manual: http://turnvater-janosch.blogspot.de/2014/04/the-awkward-fisherman-machine.html
The mechanics resemble a flying pendulum escapement (Ignatz Flying pendulum clock).
Very simple mechanics, easy to build. The required parts are shown in the video.