I just started playing with the latest version of Google SketchUp (the free version) this week and I'm really impressed with how easy and intuitive it is to use. I've been going through the video tutorials at Google and exploring on my own.

I had a couple of questions and was hoping someone here might be able to help me.

1. I know what a SKP file is, but what is an SKB file? Some of the drawings I've done seem to generate them.

2. Can you create your own materials (for use with the Paint Bucket tool) in SketchUp, or do you need SketchUp Pro to do that? If so, how do you do go about doing that? Are there any videos or tutorials available?

Thanks in advance for the help.