Initializes a static physics object of the entity using its current model. If successful, the previous physics object is removed.
This is what used by entities such as func_breakable, prop_dynamic, item_suitcharger, prop_thumper and npc_rollermine while it is in its "buried" state in the Half-Life 2 Campaign.
If the entity's current model has no physics mesh associated to it, no physics object will be created.
Clientside physics objects are broken and do not move properly in some cases. Physics objects should only created on the server or you will experience incorrect physgun beam position, prediction issues, and other unexpected behavior.