@Anthony Lane I was able to get the measurements from
@Barking mad In the hopes that the next Wittnauer Skin Diver owner's search caan be a little shorter, the measurements are as follows. The diameter is 6 mm and the thickness is 3.5 mm.
And thank you for passing along the eBay listing. Unfortunately the crown from that listing won't work but I very much appreciate you posting it. I ended up finding another watch that had a correct size service crown and from what I can tell a correct bezel as well, so I purchased that one and swapped the complete movements with dial and hands between the watches. I'll post a photo of the watch a bit later.
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