- Open subdiv from Pixar look very interesting and may help SketchUp performance and freeform modeling because user can do low poly and sub-div back and forth as needed, see 10:40
http://youtu.be/Y-3L9BOTEtw
- 3ptools Lite - 3D Modeling plugin by 3Point Studios , Sketch for freeform modeling. Very smart tool.
http://youtu.be/hAUSVwoUBiM
What do you think?

