F＃WPF - 在Viewport3D中显示一个简单的对象

I'm trying to get into generating 3D graphics in F# (as was apparent from my previous question) with very little time and very little initial knowledge of F#. I'm studying Tomas Petricek's fractal example, but I can't really make heads or tails of it. I've managed to define a window with a Viewport3D object in XAML, initialize and display it from F#. But as far as creating 3d objects in F# and displaying them goes, I'm lost in a sea of fractal generation, coordinate translation, and other calculations. Could somebody provide a simple example, of creating one really simple object in F# (a single cube, or just a triangle) and display it in the WPF window? That would be huge help. Thank you.I'm trying to get into generating 3D graphics i