Awesome plugin! I tried so many different methods of converting SketchUp files to STL files. I was able to get STL files, but they were all buggy and could not be used by my 3D printer. So I downloaded this plugin. Worked on the first try! My 3D printer happily accepted the STL file. What a relief to finally find something that works! I can't imagine why this file has any negative ratings. My best guess is that people don't understand what to do with a plugin file, and get frustrated. To add the plugin, just drop the "stl4su.rb" file into your plugins folder. On my computer, the plugins folder was located at: "C:\Program Files\Google\Google SketchUp 8\Plugins", but your computer may be slightly different. Restart SketchUp and look under the "Tools" menu. You should now see the option "Export to STL...". By the way, I'm using SketchUp Version 8.0.16846 for Windows XP. Many thanks for taking the time to write this plugin, Revar D.
Executive summary: A+; would download again. As distributed (at least for Mac), only supports SU 7. However, I found that by simply copying "/Library/Application Support/Google SketchUp 7/SketchUp/plugins/stl4su.rb" to "/Library/Application Support/Google SketchUp 8/SketchUp/plugins/" it worked just fine with SU 8. I'm sure you can do something similar under Windows. There's no documentation other than the README file, but usage is trivial: import via "File > Import..." and export via "Tools > Export to STL". One caveat: STL files have no unit or scale information in them, so you need to pay attention to your export units and your import options. That's not the fault of the plugin, it's just the way STL files are. Once I realized that you need to set your import options, it worked perfectly with both a model created in SU, and a much more elaborate part created with AutoDesk Inventor. This is probably the best tool to use to quickly validate STL parts generated by other cad software. One more caveat: this tool only allows you to export an entire model at once. There is a "Tool > Export to DXF or STL" plugin that will export a subset of a model, but I forget where I got that one.