This thesis investigates the use of 3D printing as a tool for enhancing the acoustic output of the stock speaker in a smartphone. Five custom cases are designed for an iPhone 5s and 3D printed for testing, featuring two folded horns, a two-dimensional exponential horn, a three-dimensional exponential horn, and a three-dimensional conical horn. In addition to testing the custom cases, one competitor case is also tested in an open-air chamber, with the iPhone producing white noise through an app to determine the maximum sound pressure level and frequency response. The data is then collected and analyzed, resulting in major improvements over the stock speaker. It is found that both the three-dimensional exponential and conical horn cases are at least twice as loud as the iPhone 5s without a case and feature a better frequency response. Financially, using 3D printing to manufacture the custom cases is also found to be much more advantageous, compared to the existing competitor case.