You can download a free tool to write the XML files that WPF uses to represent a GUI. These files are parsed by a Visual Basic .Net program and then used to construct the GUI. The free tool is called XamlPad, and it even comes with a feature that allows you to preview the GUI that will be created by XAML file you have writtent. Not quite a GUI Builder, but pretty close!
I work as a project land surveyor for KSN, a small civil engineering and land surveying company in Stockton, California. I am a supported of open source software development, and of open source geospatial software development specifically. I am a volunteer programmer and administrator with the JUMP Pilot Project, the non-profit group that maintains and produces OpenJUMP. I do consulting work through my small business, Redefined Horizons.
You can learn more about me at this web page.