I was asked to create a program that would assist accountant to aggregate data from various sources and generate some complicated analytical reports. Since this is an internal utility, I see it as desktop program for Windows – I choose WPF since UI may get sophisticated. But before I start actual coding, I’d like to show concept to accountant (so I won’t have to re-do things, also it is good for communication). How do I make a prototype of UI for a review?