My friend and I have been trying to figure out how to make a multi textured block for a few hours now... Image 3 is what we have right now. When we hold the block it looks fine, it has both textures on it. When we place it, it has the Pink/Blank place holder texture.
The packet class must exist on both sides. On the sender, its used to construct the binary data, on the receiver its used to read the binary data.
This is why a Context object is passed to the packet handler.