
NET Framework 3.0 CTP for the initial release of WPF but is no longer available.

It was available earlier as a Visual Studio 2005 extensions for.

The WPF designer add-in, codenamed Cider, is a WYSIWYG editor for creating WPF windows, pages and user controls. Microsoft Visual Studio is a developer-oriented IDE that contains a combination XAML editor and WPF visual designer, beginning with Visual Studio 2008.
FREE XAML DESIGNER TOOL WINDOWS
There are a number of development tools available for developing Windows Presentation Foundation applications.
