...but I had forgotten about it! I was asked to make some sample vessel sinks for a company that does designer plumbing fixtures, and I was totally stressing about how to get the drain hole right. I know the shrinkage rate of my clay (14.25%) but the tolerances are quite small and the math was yielding measurements with a lot of digits behind the decimal points. Someone -- one of the Twitterati*, actually -- reminded me of this simple device for converting wet size to finished size for any given claybody. This just needs to be bisqued and fired like any other piece, and then I can get the measurments that I need to make the opening at the bottom of the bowl fit a standard drain.
*The things I learn on Twitter! I also found out that my persistant eye twitch, which always used to happen when I got overtired, is in fact caused by low potassium. Eat a banana and it's gone! Eat a couple per week and it enver happnes at all. Off topic, I know. But interesting! I've been puttin gup with that damn twitch for a decade now, or more.