I have built a number of 10-strings, and after the first one, where I made the top too thick, I have started building them exactly like a normal 6 string, except that I add a little to the height of the braces, and I use a bridge patch, which I don't normally use. You can extend the Spanish foot a little, and make it wider. Also, leave the back say 0.5mm thicker, and make the back braces a little wider and taller. That's it.
Amateur Guitar Builder