Soap Skin & Bubble, Tensile Structures for Sketchup
Archdaily has a post regarding how the sketchup does the flexible form, for instance, before, we can actually only use sketch up to build simple form, but NOW...Tensile-structures has launched a plug-in associated with sketchup that enable the program to build a better and flexible form as samples below.
You can go the their website to download the sketch up plug-in for free! and also the video tutorials and demonstration all are available in YOUTUBE.
Tensile Structures for Sketchup (image © http://www.tensile-structures.de)
Soap Skin & Bubble (image © http://www.tensile-structures.de)