Open XML Theme Builder

The Open XML Theme Builder is a tool that helps with the creation of theme files (*.thmx) that encapsulate the visual appearance and formatting of a document in order to help create a better looking document. So it helps in creation of custom themes or modify the existing ones. Theme files can be used by Microsoft Office PowerPoint 2007, Excel 2007, and Word 2007.

If you are running Windows XP SP2, please ensure that you have the .Net Framework 3.0 and the Office 2007 Primary Interop Assemblies installed prior to using this tool.

The tool lets you open a theme, adjust any of its elements, test it, and save it. While modifying the existing themes (* .thmx files) , found in the 'Document Themes 12' folder of the Microsoft Office installation directory, be sure to first make a copy of the existing themes before tweaking them so that just in case, you can have a backup.

You can download this tool from : http://www.codeplex.com/openxmlthemebuilder

From the same link you can also get the .Net Framework 3.0 and the Office 2007 Primary Interop Assemblies required if you are installing it on Windows XP SP2.