A few years ago I was searching for an open source solution for creating 3-D scatter plots with WPF. Googling around eventually led me to this solution on CodeProject.
I have used this solution in a few of my projects since, but as far as I have been able to tell, the library has not evolved at all since the article was published in 2009.
Recently, I came across a newer 3-D drawing and charting project for WPF, namely the Helix 3D Toolkit. This project is actively developed, mainly by Øystein Bjørke, it has a vibrant user community and it is also available for Windows 8 applications (i.e. "Metro")!
First glancing at the library, I could not find any 3-D scatter plot solution. Fortunately, Øystein proposed a solution based on one of the surface plot examples in one of the sample applications. Based on Øystein's suggestion I today created a very simple 3-D scatter plot example for Helix 3D Toolkit. It looks like this:
Nothing fancy, just a proof of concept. Anyway, I made a pull request that Øystein kindly accepted, and my example is now included in the Helix 3D Toolkit example collection.