This app is CAD software for HVAC installers. It allows installers to create structurally accurate ductwork transitions by inputting a set of measurements and receiving the dimensions to draw and cut sheet metal.
The app was originally partially closed source, but between being a full time HVAC install manager, full time Computer Science student, and full time father I simply do not have the time I need to give FieldFab the tender love and care it deserves. Also, I think this app in its entirety makes for decent learning material.
Feel free to fork this and make it yours, or send me pull requests with improvements and optimizations. Want to replace the logos with your own and distribute to your own devices for your installer crew to use? Go for it! I've used this app so much to make ductwork that I almost can't imagine fabricating duct without it. This app is ad-free, and now that it is open source it's available on the app store for free.