The MeshId is the content ID of the mesh that is to be displayed on the
How do I create a mesh?
Meshes can currently only be be uploaded using
MeshParts or the game explorer. Once uploaded however, the content ID for the mesh can be used for the MeshId property. For more information on how to do this please see
Articles/Mesh Parts|this tutorial.
Note currently this property cannot be changed by scripts as the collision model of the mesh cannot be recomputed during run-time. Developers should not rely on this behavior as it is possible it may change in the future. Those looking for a custom mesh object that can be updated during runtime should use