OP,
My friend has a relative that is a watchmaker/jeweler/something. He got a watch that doesn't have a second hand, but instead has a second watch-face that moves every second. The underlying face is white (or black) and the overlying is black (or white). So, if the two are aligned, the face is totally white or totally black. As the first second ticks by, there's a sliver of black (or white). That sliver expands so the face is progressively more white, until enough seconds have ticked by that the face is all black (or white).
How baller is this watch? Here's some MS Paint to help.
The basic setup:
When its all black (or white):
The next tick:
The tick after that:
