I get asked this now and then:

“I want to use Erwin [or Visio or Visual Studio or…] to graphically design the CRM entity model, then have the actual CRM entities generated off of the tool I used to design the entities.”

While I am not aware of a direct way to do this with any ERD tools, there is a multi-step process you can use as long as your ERD designer can generate a SQL or Access database:

• Use your ERD designer to model your entities, fields and relationships
• Generate a SQL or Access database from the designer
• Use https://xrmspeedy.codeplex.com/ to generate the CRM entities from the database

Of course, you’ll need to make sure you don’t pick data types in your diagram that the xrmspeedy tool can’t translate to CRM types, but this approach can be used as a productivity enhancement to those who prefer to diagram out their entities and generated them.  Since this is an open source tool, you might consider contributing feedback if you have ideas for improvement.  After a little trial and error, I’ve found I get value out of using Visual Studio’s Entity Framework Designer plus this tool when brainstorming data models and building POCs.  Your Mileage May Vary (YMMV).

@devkeydet