I could probably make a dozen of these and never quite zero in on a series of dimensions that works for each cup. Depending on the thread I use for the stitch, the type of stitch, the idiosyncrasies of the pricking iron, and the tension of the stitch, the body can effectively be up to 1/4" "longer" or shorter than I expect. So at this point I'll just have to accept the ambiguity and account for it as best I can. The pattern's to the point where I can predict the result, if not fine-tune the seam, and that's good enough for me!
This was a really quick prototype since Ive been working on the move while pulling it together. As a result the staining is a bit sloppier than I'd like. I only let it cure for a couple hours (rather than over night) and this patchy-ness is the usual result of that.