How to apply Serializable/DeSerializable with Model3DGroup

You will have to handle the (de)serialization of Model3DGroup yourself.

Create a [Serializable]-decorated class that derives from Model3DGroup and implements the ISerializable interface[^]. If all goes well, you should be able to replace the original Model3DGroup by your SerializableModel3DGroup wherever it occurs without changing any of the surrounding code. Plus Model would be serializable.

The difficult or tedius part will then be the interface implementation, which basically means the GetObjectData(SerializationInfo, StreamingContext) method and a constructor with the same parameters. The former turns your object into a byte stream, the latter reverts the process. More precisely, you will have to make it behave like that. But how you're achieving this totally depends on the Model3DGroup class and what you want to serialize out of it (basically all information that is needed to reconstruct an instance thereof).