This is my newest cufflink.
It's a piston rod. The counter part of the cufflink is designed the way it is to show strong similarity to the special screws that assemble the two halves of the piston rod. I have detailed renderings of those screws uploaded too. I think they are a great detail to this model and should therefore be recognized in the design of the counter part. The counter part is 1cm diameter by the way, so even though it is round it should go through the hole of a shirt easily but not be able to fall out.


Note that this cufflink has a round pin. I was to lazy to make new renderings, so there is still a hexagonal one in the pics.