Designer similar as entity framework

Hello,

I have a simple question but I cannot get a correct search on google to find what I want. I'd like to develop an extension for Visual Studio that would allow me to design SharePoint content type using a designer. A bit like Entity Framework.

Basically, I'd like to develop something like that: 

http://dotnetslackers.com/images/articleimages/entity_framework_4.jpg

And behind the scene, when the user add a new property, it adds some code in a csharp file. 

Does someone have good ressources to learn that or, at least, precise term that I can use for a google search ?

Thanks a lot