I can’t find this answer after lots of research on Zbrush… I want to use diameter and length measurements of the same kind of trees and their branches, and simply type them in, resulting in a base tree. The trees have similar structure of beams, but I don’t want to have to keep sculpting from scratch each time. Can I have a “skeleton” of multiple Zspheres that are assigned measurements first, thus giving me a more accurate “base tree” where I can go in to add finer details?
I don’t think it’s possible to do exactly what you are asking but you may find that the ZTree plugin, which has a lot of options for creating trees using ZSpheres, is sufficient for your needs. The plugin is free and you can get it here:
https://gumroad.com/l/juCmV so you could download the ZBrush Trial version and give it a go before purchasing.