My Account 
Okay so after 4 days I have my models down to a workable size without much detail loss. I have exported the files as OBJ and import them into Simplfy3D. I have an issue with non-manifold edges and self-intersecting surfaces.
I have tried everything I can think of in ZBrush to stop this, I have made live booleans, Merged, baked layers, check mesh integrity and everything leave ZBrush in good order but Simplfy3D still gives me those errors.
My process is to import an OBJ template file, either make a polymesh cube then size it to the template, then dynamesh.I have also tried to separate the top of the template and increase its height, then dynamesh. after detailing then merge them into one tool and export as a new OBJ. I will include a 2×4 test tile, Incase anyone can help.
Thank you for any assistance,
Sean