notes for Booleans in zbrush:
tool -> subtool -> append then select one to scale it click on move button at top then find blue/green/red squares on the gizmo top -> click move tool and position object tool -> subtool -> click boolean icons (overlapping circles) second icon is substact click Live Boolean on top to enable it to merge shapes -> tool -> subtool -> boolean click DSdiv click Make Boolean Mesh (this creates a new tool) (tool -> select newly created tool) this works with dynamesh too, just need to refresh!