Picture this—Sal has a small business providing customized iPhone cases. He takes orders to print customer's names on a phone case in a color of their choice.

To create a quality case, Sal precisely measured his own iPhone with a pair of calipers, noting overall dimensions and locations of features like the power jack, volume buttons, and the camera. From this data, he modeled a case in SketchUp, printed it, and tested it for fit. The first case was a bit too tight, so he increased the dimensions in SketchUp and tested the print again. After 4 iterations between SketchUp and the printed part, the case snapped crisply onto his phone, all the openings worked well when plugging his phone in and Sal was happy with the case.