I'm Dave Penney, a Professional Engineer (PE) in the San Francisco Bay Area. I've run my own consulting firm since 1990, designing HVAC and plumbing systems.
We have used SketchUp since version 5. In 2007, we developed some extensions for implementing BIM (Building Information Modeling) for designing large plumbing systems.
Over the years, we have continued to enhance and improve this software. FlatText and DPLineStyler are both spinoffs of this project.