Ugh. That was painful... After lots of procrastination, I finally took the time out to write the online tutorial for drawing in 3-dimensions in Processing. Drawing 3d in Processing is basically the same as drawing in 3d in OpenGL, so it takes a little bit of theory to get up to speed. I'm still not sure I got it down to its essential elements -- and so far I haven't added anything about drawing vertex-based figures -- but at least it's a start I can work off of.
A lot of my students are interested in 3d, but don't have any experience programing it vertex-by-vertex. Some have done some brilliant work with various 3d engines, for example this artificial life installation for Arborescence '05 by Vincent Cogne and Yannick Aïvayan built using the Doom3 engine (we had a lot of fun fiddling with that one). But unfortunately over the years the Atelier Hypermedia has been pegged as a 2d shop for a really stupid reason: that's what people used to call it before I arrived. So Processing has been a nice way to correct that misconception as ultimately drawing 3d in Processing is the same as drawing 2d, you just rotate the drawing space.
As with all the other tutorials in my Processing Programming class, everything is in French, but you might be able to get by with a robot translator and the many screenshots and code samples sprinkled throughout.