There are some pretty sweet pencil & paper + app solutions out there, that allow you to draw the UI and take pictures of it. http://maniacdev.com/2013/06/nifty-

There are some pretty sweet pencil & paper + app solutions out there, that allow you to draw the UI and take pictures of it. http://maniacdev.com/2013/06/nifty-iphone-app-allowing-you-to-turn-hand-drawn-app-mockups-into-interactive-prototypes http://maniacdev.com/2013/06/nifty-iphone-app-allowing-you-t...