How to generate a twisting form by sketch up?

One asked how to build a twisting form in sketchup, let's start with a simple form for your experiment and better understanding, here we go...

First, after building the form as shown in picture, then select only the top surface and rotate it, the twisting form will be automatically generated... try it out!

sketch up effect with a lightlight color

car showroom proposal

Here is the sample of creating the sketch up effect with a lightlighting color that expressing your architectural ideas. This features can be colored in photoshop or even in sketch-up before exporting to Jpeg file.