The free Intermediate Data Format Plug-In is the first plug-in module for PCB123 based on the v. 3.1 Software Developer’s Kit. Enables import of PCB designs for use in mechanical and electrical CAD systems in a bidirectional, neutral format within the ECOsystem Design Environment. Imports outline definitions of the PCB as specified by the mechanical CAD tool, synchronizing the mechanical design work with the PCB development work.
 
Sunstone Circuits, http://www.sunstone.com/products-services/cad-software.aspx