Great job Monger, you have far more patience than I do!
I know you can hollow a model with Zbrush but I’ve never managed to figure it out. I hollow models out with Geomagic Studio and its super easy with it. Checkout this thread: Hollow/Shell STL file methods?
What I haven’t figured out but really havent tried to much, is how to put a hole in an STL model so it doesnt just trap resin.
I’ve been drilling some holes when theyre done though otherwise they blowout/crack up.