Download the Visual Studio add-in for SQL Server Compact 3.5 and 4.0 from here

SQL Server Compact Toolbox 3.2–Visual Guide of new features

New features:
- Added new menu item to export a SQL Server database to a SQL Server Compact 4.0 sdf file in a single workflow
- Server export files can now optionally include schema name as part of table name
- Now using Red Gate SmartAssembly for quality improvement (error reporting and feature usage tracking)

Improvements:
- SQL Server tables displayed are properly sorted by schema.name
- Notifying user that 3.5 SP2 is required for many features to Work
- Improved SQL Server DGML diagram
- Improved treeview performance

Bug fixes:
- SQL Editor button texts now visible with dark theme
- Merge Replication dialog fixed to work with "Windows Integrated Authentication"
- Updated scripting API, with FK bug fixes