@Rei: tried something similar in the past, but based on several cube meshes. One cubemesh at the start, and selected cubic parts removed etc. But required one entity per Block >.<.
Are you going to make the source public?
MY Website with news of my projects: (for example my current Muliplayer Bomberman, GenesisPrecompiler for LiteC and TileMaster, an easy to use Tile editor) Sparetime-Development