Can I take a modular mesh, say a piece of terrain, which has no thickness and only 1 side, somehow dynamesh it and not result in many holes around the edge? So far I only manage to sub-divide it, but not dynamesh. Any tricks to this?
You can add thickness to something you want to dynamesh by using morph targets. Store Morph target, move your mesh down, switch morph target, then generate the diff mesh.