Can I use the Ruby API to generate a Bill of Materials from a model?
The short answer: yes. The long answer: a bill of materials is a complex thing that is different for each industry and user group. Since SketchUp is a surface modeler that doesn’t necessarily know that the box you’re drawing is, say, a piece of lumber, there could be a fair amount of work that your script would need to do to get the results that you want. But that’s why it’s a generic programming API: you can do whatever you want with it.
