eZ Publish 4.x compatible fork of ezchangeclass on projects.ez.no. Original work by Bartek Modzelewski.
http://projects.ez.no/object_content_class_change

This extension allows to change a content object's content class. Useful when
refactoring an existing installation, i.e. towards organizational entities.

Usage:
Click on the context menu entry of a given node in the admin tree.

Features:
- Two ways to change a content object's class:
- A. Change an existing object's content class without creating a new object (thus
  keeping the existing node). All needed new attributes will be
  created automatically, and all data in it will be copied.
- B. Copy an existing object to another class (thus creating a new object and node)
- Mapping between attributes of classes
- Possibilty to map between different datatypes if the same db table
  attribute is used (for ex. data_text -> data_text) - simple
  conversion can be set in changeclass.ini file
- Batch conversion of existing objects, select 'Generate console
  parameters' on step 2 to get all the info.
- Handles archived and other object versions as well.