It was 2,8 mm. After soaking and swelling, it's now about 4 mm. It took me quite a while to wrestle with it. A friend had offered me his help in case of need, but I wanted to brag and do it all by myself. Bad idea...

But the feeling is really smooth when I touch it, though I suppose it's not quite dry yet.
The one I'm gonna mount on the tres dos is "only" 2,1 mm. It's gonna be a children play in comparison.
I'm still 'shellacking' the tres dos. I'll mount the skin at the end of the week.