Visual Studio 2010 does support LocalDB provided the new SQL Server Developer Tool (SSDT) is installed. After installing SSDT you need to create a SQL Server Database project as shown.
The SQL Server Database that is used within the project is the LocalDB. Here you can call up the table designer using Add Table as shown.
This document was edited to remove the error which gave the impression that this is a C# project. It is actually a SQL Server project.