For the final stage of our design process, we had to create interactive prototypes in PowerPoint. I found this part maddening, because I had to teach myself some Visual Basic in order to create the input fields, action buttons, and drop-down inputs.
You can view one of my usability tests on this final prototype below. Apologies in advance for the audio quality; my test subject has a naturally quiet voice.
(Yes, I offered him tacos at the end of the video as payment for his time.)