redesign in progress. massive update as you can see. Now the blocks, items and tileEntities are all in single classes inside the minecraft package. These classes will store a reference to the GameObject class, which is the internal representation I use. This conforms to the observation I said earlier: these three are no different from each other and tightly coupled, so shall be represented by a single class, not three. Any new objects can be created by creating a new GameObject instance, and assign to the Block, Item, or TileEntity classes.