The charette model featured a "human sundial," which I didn't reproduce with an actual human, but instead modeled a more traditional, working sundial which tells the hour based on shadows. You need to tell SketchUp where on Earth the sundial is located, then let SketchUp figure out the shadows.
Once you have your sundial, this project shows how to save scenes you can use to see its shadow based on the hour and season.
The people and trees in the classroom model from the charette are translucent silhouettes - a nice, artistic way to show entourage in a model. This project shows how to populate a model with silhouettes of poeple, and how to make them translucent.
Anyone can design anything in 3D! http://www.3dvinci.net/