For the Sumry (later re-launched as STiL) app that I worked on with photographer and developer Paul Freeman (http://paulfreeman.com/), I made a few paper prototypes. The first prototype performed capture in portrait mode, which was consistent with Instagram, which was just getting big at the time. But the format turned out not to be the best for the ‘sound slideshow’ that we eventually wanted to make.
The second prototype was closer to how it ended up working. But in the end, we used a square format for the images. But I captured all the functions (record, re-mix, view, publish) that ended up being in the app that was finally launched.