Download the Visual Studio add-in for SQL Server Compact 4.0 and 3.5 from here
Standalone version of (most of) the same functionality as the add-in, for SQL Server Compact 3.5 SP2. (Let me know if you miss anything)
Useful for anyone not having Visual Studio Professional or higher installed.
Requires .NET 4.0 and the SQL Server Compact 3.5 SP2 runtime