[Beginner's question] Drawing / Visual / Shape confusion...

I followed this sample:
http://www.cubido.at/Blog/tabid/176/...1/Default.aspx

But the XAML for the analogic clock is such a mess (non-reusable custom
value converter, 120 line of terse XAML, etc..) That I though: "hey, how
about I write a ... templatable class .. that does some of this rendering)
and then still a templatable Clock content, but use my Drawing, or Visual,
or Shape, or whatever.

The easiest class to implement a content seems to be a UIElement, I could
override OnRender(), any other suggestion?