I had this same problem last week and still can't figure it out..... I have been trying to create a material library for standard colors at work. SU's native material files won't export and duplicated materials revert back to the original .skm name when the program relaunches. I took it a step further by adding a new materials folder under app support > Sketchup > Materials. Then I copied and pasted materials from SU's colors, renaming the .skms to building standard materials (ex. Color_D04.skm to Sheathing.skm) When I opened SU the newly created material folder was listed however all the materials reverted back to there original name? Do I have to create my own .skms in order to rename these materials?

No. I can't open it in my downloads file .......I open .rb all the time when I'm installing plugins but I can't open .rbx for some reason?

I'm super excited about this plugin!........but the file isn't opening on my mac?!?

Does anyone know how I can actually smooth my vertices so I can export to stl and 3d print? I have been using SU for years and typically I work with architectural interiors and space design. I don't usually deal with organic forms but a friend came to me for a prototype design and he wants it 3d printed. After a week of cleaning up the model I was given and reforming it to new specs I exported it to .stl. I was really surprised when I was told the rough faces on the stl file were the actual faces and SU does a false vertex smoothing. Is there a way to salvage my model? I was told it was impossible to completly smooth the geometry in sketch up and I was going to have to remodel the prototype in another program. I have faith in plugins .... just need to find the right one! Any thoughts?!?! - Tiffany