If you like keychains better than cufflinks here is one of the piston rod.
The best thing is it doesn't even need an ear for any chain. ;)
There are renderings of this one in the cufflink model which is exactly the same except for the pin that the cufflink needs and the size.
Here is the cufflink of this model:
3.984 w x
1.758 d x
1.569 w x
0.692 d x