You might enjoy reviewing a past thread from Alex on the VC coin watch click here to see the post
It really is a fascinating sub-catagory of watches...beginning with coin purse or pocket watches, then coin pendant watches, and finally coin wristwatches.
In addition to the beautiful work of Vacheron, Patek, Piaget and Audemars at the high end, makers such as Bueche-Girod, Eska, LeCoultre and Universal Geneve also made coin watches. Of course, Corum is well know for their version in continuous production since 1965, mostly with the simple non-hidden case. Their latest model has an automatic movement.
Here are a few movement pics from the internet:
And the superb VC caliber 1003 skeleton (pic courtesy of Foversta)